presenting part in vertex presentation

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Fetal Presentation, Position, and Lie (Including Breech Presentation)

, MD, Children's Hospital of Philadelphia

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Abnormal fetal lie or presentation may occur due to fetal size, fetal anomalies, uterine structural abnormalities, multiple gestation, or other factors. Diagnosis is by examination or ultrasonography. Management is with physical maneuvers to reposition the fetus, operative vaginal delivery Operative Vaginal Delivery Operative vaginal delivery involves application of forceps or a vacuum extractor to the fetal head to assist during the second stage of labor and facilitate delivery. Indications for forceps... read more , or cesarean delivery Cesarean Delivery Cesarean delivery is surgical delivery by incision into the uterus. The rate of cesarean delivery was 32% in the United States in 2021 (see March of Dimes: Delivery Method). The rate has fluctuated... read more .

Terms that describe the fetus in relation to the uterus, cervix, and maternal pelvis are

Fetal presentation: Fetal part that overlies the maternal pelvic inlet; vertex (cephalic), face, brow, breech, shoulder, funic (umbilical cord), or compound (more than one part, eg, shoulder and hand)

Fetal position: Relation of the presenting part to an anatomic axis; for transverse presentation, occiput anterior, occiput posterior, occiput transverse

Fetal lie: Relation of the fetus to the long axis of the uterus; longitudinal, oblique, or transverse

Normal fetal lie is longitudinal, normal presentation is vertex, and occiput anterior is the most common position.

Abnormal fetal lie, presentation, or position may occur with

Fetopelvic disproportion (fetus too large for the pelvic inlet)

Fetal congenital anomalies

Uterine structural abnormalities (eg, fibroids, synechiae)

Multiple gestation

Several common types of abnormal lie or presentation are discussed here.

Transverse lie

Fetal position is transverse, with the fetal long axis oblique or perpendicular rather than parallel to the maternal long axis. Transverse lie is often accompanied by shoulder presentation, which requires cesarean delivery.

Breech presentation

There are several types of breech presentation.

Frank breech: The fetal hips are flexed, and the knees extended (pike position).

Complete breech: The fetus seems to be sitting with hips and knees flexed.

Single or double footling presentation: One or both legs are completely extended and present before the buttocks.

Types of breech presentations

Breech presentation makes delivery difficult ,primarily because the presenting part is a poor dilating wedge. Having a poor dilating wedge can lead to incomplete cervical dilation, because the presenting part is narrower than the head that follows. The head, which is the part with the largest diameter, can then be trapped during delivery.

Additionally, the trapped fetal head can compress the umbilical cord if the fetal umbilicus is visible at the introitus, particularly in primiparas whose pelvic tissues have not been dilated by previous deliveries. Umbilical cord compression may cause fetal hypoxemia.

Predisposing factors for breech presentation include

Preterm labor Preterm Labor Labor (regular uterine contractions resulting in cervical change) that begins before 37 weeks gestation is considered preterm. Risk factors include prelabor rupture of membranes, uterine abnormalities... read more

Multiple gestation Multifetal Pregnancy Multifetal pregnancy is presence of > 1 fetus in the uterus. Multifetal (multiple) pregnancy occurs in up to 1 of 30 deliveries. Risk factors for multiple pregnancy include Ovarian stimulation... read more

Uterine abnormalities

Fetal anomalies

If delivery is vaginal, breech presentation may increase risk of

Umbilical cord prolapse

Perinatal death

It is best to detect abnormal fetal lie or presentation before delivery. During routine prenatal care, clinicians assess fetal lie and presentation with physical examination in the late third trimester. Ultrasonography can also be done. If breech presentation is detected, external cephalic version can sometimes move the fetus to vertex presentation before labor, usually at 37 or 38 weeks. This technique involves gently pressing on the maternal abdomen to reposition the fetus. A dose of a short-acting tocolytic ( terbutaline 0.25 mg subcutaneously) may help. The success rate is about 50 to 75%. For persistent abnormal lie or presentation, cesarean delivery is usually done at 39 weeks or when the woman presents in labor.

Face or brow presentation

In face presentation, the head is hyperextended, and position is designated by the position of the chin (mentum). When the chin is posterior, the head is less likely to rotate and less likely to deliver vaginally, necessitating cesarean delivery.

Brow presentation usually converts spontaneously to vertex or face presentation.

Occiput posterior position

The most common abnormal position is occiput posterior.

The fetal neck is usually somewhat deflexed; thus, a larger diameter of the head must pass through the pelvis.

Progress may arrest in the second phase of labor. Operative vaginal delivery Operative Vaginal Delivery Operative vaginal delivery involves application of forceps or a vacuum extractor to the fetal head to assist during the second stage of labor and facilitate delivery. Indications for forceps... read more or cesarean delivery Cesarean Delivery Cesarean delivery is surgical delivery by incision into the uterus. The rate of cesarean delivery was 32% in the United States in 2021 (see March of Dimes: Delivery Method). The rate has fluctuated... read more is often required.

Position and Presentation of the Fetus

If a fetus is in the occiput posterior position, operative vaginal delivery or cesarean delivery is often required.

In breech presentation, the presenting part is a poor dilating wedge, which can cause the head to be trapped during delivery, often compressing the umbilical cord.

For breech presentation, usually do cesarean delivery at 39 weeks or during labor, but external cephalic version is sometimes successful before labor, usually at 37 or 38 weeks.

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StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

StatPearls [Internet].

Delivery, face and brow presentation.

Julija Makajeva ; Mohsina Ashraf .

Affiliations

Last Update: January 9, 2023 .

• Continuing Education Activity

Face and brow presentation is a malpresentation during labor when the presenting part is either the face or, in the case of brow presentation, it is the area between the orbital ridge and the anterior fontanelle. This activity reviews the evaluation and management of these two presentations and explains the role of the interprofessional team in managing delivery safely for both the mother and the baby.

• Describe the mechanism of labor in the face and brow presentation.
• Summarize potential maternal and fetal complications during the face and brow presentations.
• Review different management approaches for the face and brow presentation.
• Outline some interprofessional strategies that will improve patient outcomes in delivery cases with face and brow presentation issues.
• Introduction

The term presentation describes the leading part of the fetus or the anatomical structure closest to the maternal pelvic inlet during labor. The presentation can roughly be divided into the following classifications: cephalic, breech, shoulder, and compound. Cephalic presentation is the most common and can be further subclassified as vertex, sinciput, brow, face, and chin. The most common presentation in term labor is the vertex, where the fetal neck is flexed to the chin, minimizing the head circumference.

Face presentation – an abnormal form of cephalic presentation where the presenting part is mentum. This typically occurs because of hyperextension of the neck and the occiput touching the fetal back. Incidence of face presentation is rare, accounting for approximately 1 in 600 of all presentations. [1] [2] [3]

In brow presentation, the neck is not extended as much as in face presentation, and the leading part is the area between the anterior fontanelle and the orbital ridges. Brow presentation is considered the rarest of all malpresentation with a prevalence of 1 in 500 to 1 in 4000 deliveries. [3]

Both face and brow presentations occur due to extension of the fetal neck instead of flexion; therefore, conditions that would lead to hyperextension or prevent flexion of the fetal neck can all contribute to face or brow presentation. These risk factors may be related to either the mother or the fetus. Maternal risk factors are preterm delivery, contracted maternal pelvis, platypelloid pelvis, multiparity, previous cesarean section, black race. Fetal risk factors include anencephaly, multiple loops of cord around the neck, masses of the neck, macrosomia, polyhydramnios. [2] [4] [5]

These malpresentations are usually diagnosed during the second stage of labor when performing a digital examination. It is possible to palpate orbital ridges, nose, malar eminences, mentum, mouth, gums, and chin in face presentation. Based on the position of the chin, face presentation can be further divided into mentum anterior, posterior, or transverse. In brow presentation, anterior fontanelle and face can be palpated except for the mouth and the chin. Brow presentation can then be further described based on the position of the anterior fontanelle as frontal anterior, posterior, or transverse.

Diagnosing the exact presentation can be challenging, and face presentation may be misdiagnosed as frank breech. To avoid any confusion, a bedside ultrasound scan can be performed. [6]  The ultrasound imaging can show a reduced angle between the occiput and the spine or, the chin is separated from the chest. However, ultrasound does not provide much predicting value in the outcome of the labor. [7]

• Anatomy and Physiology

Before discussing the mechanism of labor in the face or brow presentation, it is crucial to highlight some anatomical landmarks and their measurements. 

Planes and Diameters of the Pelvis

The three most important planes in the female pelvis are the pelvic inlet, mid pelvis, and pelvic outlet. 

Four diameters can describe the pelvic inlet: anteroposterior, transverse, and two obliques. Furthermore, based on the different landmarks on the pelvic inlet, there are three different anteroposterior diameters, named conjugates: true conjugate, obstetrical conjugate, and diagonal conjugate. Only the latter can be measured directly during the obstetric examination. The shortest of these three diameters is obstetrical conjugate, which measures approximately 10.5 cm and is a distance between the sacral promontory and 1 cm below the upper border of the symphysis pubis. This measurement is clinically significant as the fetal head must pass through this diameter during the engagement phase. The transverse diameter measures about 13.5cm and is the widest distance between the innominate line on both sides. 

The shortest distance in the mid pelvis is the interspinous diameter and usually is only about 10 cm. 

Fetal Skull Diameters

There are six distinguished longitudinal fetal skull diameters:

• Suboccipito-bregmatic: from the center of anterior fontanelle (bregma) to the occipital protuberance, measuring 9.5 cm. This is the presenting diameter in vertex presentation. 
• Suboccipito-frontal: from the anterior part of bregma to the occipital protuberance, measuring 10 cm 
• Occipito-frontal: from the root of the nose to the most prominent part of the occiput, measuring 11.5cm
• Submento-bregmatic: from the center of the bregma to the angle of the mandible, measuring 9.5 cm. This is the presenting diameter in face presentation where the neck is hyperextended. 
• Submento-vertical: from the midpoint between fontanelles and the angle of the mandible, measuring 11.5cm 
• Occipito-mental: from the midpoint between fontanelles and the tip of the chin, measuring 13.5 cm. It is the presenting diameter in brow presentation. 

Cardinal Movements of Normal Labor

• Neck flexion
• Internal rotation
• Extension (delivers head)
• External rotation (Restitution)
• Expulsion (delivery of anterior and posterior shoulders)

Some of the key movements are not possible in the face or brow presentations.  

Based on the information provided above, it is obvious that labor will be arrested in brow presentation unless it spontaneously changes to face or vertex, as the occipito-mental diameter of the fetal head is significantly wider than the smallest diameter of the female pelvis. Face presentation can, however, be delivered vaginally, and further mechanisms of face delivery will be explained in later sections.

• Indications

As mentioned previously, spontaneous vaginal delivery can be successful in face presentation. However, the main indication for vaginal delivery in such circumstances would be a maternal choice. It is crucial to have a thorough conversation with a mother, explaining the risks and benefits of vaginal delivery with face presentation and a cesarean section. Informed consent and creating a rapport with the mother is an essential aspect of safe and successful labor.

• Contraindications

Vaginal delivery of face presentation is contraindicated if the mentum is lying posteriorly or is in a transverse position. In such a scenario, the fetal brow is pressing against the maternal symphysis pubis, and the short fetal neck, which is already maximally extended, cannot span the surface of the maternal sacrum. In this position, the diameter of the head is larger than the maternal pelvis, and it cannot descend through the birth canal. Therefore the cesarean section is recommended as the safest mode of delivery for mentum posterior face presentations. 

Attempts to manually convert face presentation to vertex, manual or forceps rotation of the persistent posterior chin to anterior are contraindicated as they can be dangerous.

Persistent brow presentation itself is a contraindication for vaginal delivery unless the fetus is significantly small or the maternal pelvis is large.

Continuous electronic fetal heart rate monitoring is recommended for face and brow presentations, as heart rate abnormalities are common in these scenarios. One study found that only 14% of the cases with face presentation had no abnormal traces on the cardiotocograph. [8] It is advised to use external transducer devices to prevent damage to the eyes. When internal monitoring is inevitable, it is suggested to place monitoring devices on bony parts carefully. 

People who are usually involved in the delivery of face/ brow presentation are:

• Experienced midwife, preferably looking after laboring woman 1:1
• Senior obstetrician 
• Neonatal team - in case of need for resuscitation 
• Anesthetic team - to provide necessary pain control (e.g., epidural)
• Theatre team  - in case of failure to progress and an emergency cesarean section will be required.
• Preparation

No specific preparation is required for face or brow presentation. However, it is essential to discuss the labor options with the mother and birthing partner and inform members of the neonatal, anesthetic, and theatre co-ordinating teams.

• Technique or Treatment

Mechanism of Labor in Face Presentation

During contractions, the pressure exerted by the fundus of the uterus on the fetus and pressure of amniotic fluid initiate descent. During this descent, the fetal neck extends instead of flexing. The internal rotation determines the outcome of delivery, if the fetal chin rotates posteriorly, vaginal delivery would not be possible, and cesarean section is permitted. The approach towards mentum-posterior delivery should be individualized, as the cases are rare. Expectant management is acceptable in multiparous women with small fetuses, as a spontaneous mentum-anterior rotation can occur. However, there should be a low threshold for cesarean section in primigravida women or women with large fetuses.

When the fetal chin is rotated towards maternal symphysis pubis as described as mentum-anterior; in these cases further descend through the vaginal canal continues with approximately 73% cases deliver spontaneously. [9] Fetal mentum presses on the maternal symphysis pubis, and the head is delivered by flexion. The occiput is pointing towards the maternal back, and external rotation happens. Shoulders are delivered in the same manner as in vertex delivery.

Mechanism of Labor in Brow Presentation

As this presentation is considered unstable, it is usually converted into a face or an occiput presentation. Due to the cephalic diameter being wider than the maternal pelvis, the fetal head cannot engage; thus, brow delivery cannot take place. Unless the fetus is small or the pelvis is very wide, the prognosis for vaginal delivery is poor. With persistent brow presentation, a cesarean section is required for safe delivery.

• Complications

As the cesarean section is becoming a more accessible mode of delivery in malpresentations, the incidence of maternal and fetal morbidity and mortality during face presentation has dropped significantly. [10]

However, there are still some complications associated with the nature of labor in face presentation. Due to the fetal head position, it is more challenging for the head to engage in the birth canal and descend, resulting in prolonged labor.

Prolonged labor itself can provoke foetal distress and arrhythmias. If the labor arrests or signs of fetal distress appear on CTG, the recommended next step in management is an emergency cesarean section, which in itself carries a myriad of operative and post-operative complications.

Finally, due to the nature of the fetal position and prolonged duration of labor in face presentation, neonates develop significant edema of the skull and face. Swelling of the fetal airway may also be present, resulting in respiratory distress after birth and possible intubation.

• Clinical Significance

During vertex presentation, the fetal head flexes, bringing the chin to the chest, forming the smallest possible fetal head diameter, measuring approximately 9.5cm. With face and brow presentation, the neck hyperextends, resulting in greater cephalic diameters. As a result, the fetal head will engage later, and labor will progress more slowly. Failure to progress in labor is also more common in both presentations compared to vertex presentation.

Furthermore, when the fetal chin is in a posterior position, this prevents further flexion of the fetal neck, as browns are pressing on the symphysis pubis. As a result, descend through the birth canal is impossible. Such presentation is considered undeliverable vaginally and requires an emergency cesarean section.

Manual attempts to change face presentation to vertex, manual or forceps rotation to mentum anterior are considered dangerous and are discouraged.

• Enhancing Healthcare Team Outcomes

A multidisciplinary team of healthcare experts supports the woman and her child during labor and the perinatal period. For a face or brow presentation to be appropriately diagnosed, an experienced midwife and obstetrician must be involved in the vaginal examination and labor monitoring. As fetal anomalies, such as anencephaly or goiter, can contribute to face presentation, sonographers experienced in antenatal scanning should also be involved in the care. It is advised to inform the anesthetic and neonatal teams in advance of the possible need for emergency cesarean section and resuscitation of the neonate. [11] [12]

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Disclosure: Julija Makajeva declares no relevant financial relationships with ineligible companies.

Disclosure: Mohsina Ashraf declares no relevant financial relationships with ineligible companies.

This book is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits others to distribute the work, provided that the article is not altered or used commercially. You are not required to obtain permission to distribute this article, provided that you credit the author and journal.

• Cite this Page Makajeva J, Ashraf M. Delivery, Face and Brow Presentation. [Updated 2023 Jan 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

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Malpresentation, Malposition, Cephalopelvic Disproportion and Obstetric Procedures

26 Malpresentation, Malposition, Cephalopelvic Disproportion and Obstetric Procedures Kim Hinshaw 1,2 and Sabaratnam Arulkumaran 3 1 Sunderland Royal Hospital, Sunderland, UK 2 University of Sunderland, Sunderland, UK 3 St George’s University of London, London, UK Malpresentation, malposition and cephalopelvic disproportion Definitions The vertex is a diamond‐shaped area on the fetal skull bounded by the anterior and posterior fontanelles and laterally by the parietal eminences. Vertex presentation is found in 95% of labours at term and is associated with flexion of the fetal head. Breech, brow, face and shoulder presentations constitute the remaining 5% and are collectively known as malpresentations . Their aetiology is usually unknown, but associations include macrosomia, multiparity, polyhydramnios, multiple pregnancy, placenta praevia, preterm labour, and anomalies of the uterus or pelvis (congenital or acquired, e.g. lower segment fibroids) and more rarely the fetus. The denominator is a laterally sited bony eminence on the presenting part (‘occiput’ for vertex presentation, ‘mentum’ for face, ‘acromium’ for shoulder and ‘sacrum’ for breech). The position of the presenting part is defined by the relationship of the denominator to the maternal bony pelvis. The vertex enters the pelvis in the occipito‐transverse (OT) position and during descent rotates to an occipito‐anterior (OA) position in 90% of cases. This position is associated with a well‐flexed head, allowing the smallest anteroposterior (suboccipito‐bregmatic) and lateral (biparietal) diameters to pass through the pelvis (both 9.5 cm). Malposition occurs when the occiput remains in a tranverse or posterior position as labour progresses. Persistent malposition results in deflexion with a larger anteroposterior diameter presenting (occipito‐frontal 11.5 cm). It is associated with increasing degrees of anterior or posterior asynclitism , with one of the parietal bones preceding the sagittal suture (in posterior asynclitism, the posterior parietal bone leads; Fig. 26.1 ). Significant degrees of asynclitism can result in labour dystocia and a higher risk of operative delivery [1] . Fig. 26.1 Posterior asynclitism of the vertex: posterior parietal bone presenting below the sagittal suture. In most cases, flexion occurs as the vertex descends onto the pelvic floor, leading to correction of the malposition and a high chance of spontaneous delivery. The level of the presenting part should be critically assessed as labour progresses. On abdominal examination, the head should descend until it is no more than 1/5 palpable in the late first stage. On vaginal examination the presenting part is assessed relative to the level of the ischial spines. Care must be taken to assess the level using the lowest bony part . Malposition is associated with increased moulding of the fetal skull and a large caput succedaneum, which may give false reassurance about the true degree of descent. In modern obstetric practice, operative vaginal delivery is not attempted if the leading edge of the skull is above the ischial spines (i.e. above ‘0’ station; Fig. 26.2 ). Fig. 26.2 Level of the presenting part relative to the ischial spines. Malpresentations Breech presentation The incidence of breech presentation varies according to gestation: 20% at 30 weeks falling to 4% by term. The aetiology of most breech presentations at term is unclear but known factors to consider include placenta praevia, polyhydramnios, bicornuate uterus, fibroids and, rarely, spina bifida or hydrocephaly. Types of breech presentation Between 50 and 70% of breech presentations manifest with hips flexed and knees extended (extended breech) Complete (or flexed) breech is more common in multiparous women and constitutes 5–10% at term (hips and knees flexed; Fig. 26.3 ). Incomplete or footling breech (10–30%) presents with one or both hips extended, or one or both feet presenting and is most strongly assoiated with cord prolapse (5–10%). Knee presentation is rare. Fig. 26.3 The common types of breech presentation. Clinical diagnosis may miss up to 20% of breech presentations, relying on identifying the head as a distinct hard spherical hard mass to one or other side under the hypochondrium which distinctly ‘ballots’. In such cases the breech is said to feel broader and an old adage reminds us: ‘Beware the deeply engaged head – it is probably a breech!’ Auscultation may locate the fetal heart above the maternal umbilicus and ultrasound confirmation should be considered. Antenatal management If breech presentation is suspected at 36 weeks, ultrasound assessment is recommended as it allows a comprehensive assessment of the type of breech, placental site, estimated fetal weight, confirmation of normality and exclusion of nuchal cord or hyperextension of the fetal neck. External cephalic version (ECV) is encouraged after 36 or more weeks as the chance of spontaneous version to cephalic presentation after 37 weeks is only 8%. Absolute contraindications are relatively few but include placenta praevia, bleeding within the last 7 days, abnormal cardiotocography (CTG), major uterine anomaly, ruptured membranes and multiple pregnancy [2] . Couples should receive counselling about the procedure and its success rates and complications, and the subsequent management of persistent breech presentation. Tocolysis increases the likelihood of success, with average rates of 50% (range 30–80%). Women should be made aware that even with a cephalic presentation following ECV, labour is still associated with a higher rate of obstetric intervention than when ECV has not been required. ECV should be performed in a setting where urgent caesarean section (CS) is available in case of fetal compromise during or soon after ECV. CTG for 30–40 min prior to and after ECV should provide confirmation of fetal health. The chance of success is greater with multiparity, flexed breech presentation and an adequate liquor volume. The use of moxibustion at 33–35 weeks, in combination with acupuncture, may reduce the numbers of births by CS. Training specialist midwives is potentially cost‐efficient with success rates comparable to consultant‐led services (51–66%) [3] . The first step in ECV involves disengaging the breech by moving the fetus up and away from the pelvis, shifting it to a sideways position, followed by a forward somersault to move the head to the lower pole; if this fails a backward somersault can be tried. The need for emergency delivery by CS because of suspected fetal compromise is estimated to be 0.5%. Mothers who are rhesus‐negative should have a Kleihauer–Betke test after the procedure and receive anti‐D. If ECV is unsuccessful, women who are keen to avoid CS may be offered a repeat attempt under neuraxial blockade. This increases the chances of success (58.4% vs. 43.1%; relative risk, RR 1.44, 95% CI 1.27–1.64) and reduces the incidence of CS (46.0% vs. 55.3%; RR 0.83, 95% CI 0.71–0.97) [4] . Otherwise appropriate counselling about the options of elective CS or assisted vaginal breech delivery should be offered. Deciding mode of delivery Despite increasing evidence supporting elective CS for breech delivery at term, controversy and debate continue among professional groups. Breech presentation at term diagnosed antenatally . The Term Breech Trial is the largest published randomized controlled trial where the primary outcome (serious perinatal morbidity and mortality) favoured planned CS over planned vaginal birth: 17/1039 (1.6%) versus 50/1039 (5.0%; RR 0.33, 95% CI 0.19–0.56; P <0.0001) [5] . The trial concluded that ‘planned CS is better than planned VB for the term fetus in the breech presentation; serious maternal complications are similar between the groups’. This has significantly changed practice in many countries despite continuing debate and criticism about the trial design and intepretation of outcomes. However, the latest systematic review has confirmed a significant increased perinatal risk associated with planned vaginal birth [6] . Breech at term diagnosed in labour and preterm breech delivery . Observational trials of term breech ‘undiagnosed’ until presentation in labour confirm that this group has a high vaginal delivery rate with relatively low perinatal morbidity. In a similar vein, the evidence to guide best practice for delivery of the preterm breech remains equivocal, decisions often being based on individual interpretation of the data and local custom and practice. Conducting a vaginal breech delivery For women who wish to deliver vaginally, antenatal selection aims to ensure optimal outcome for mother and baby but remains relatively subjective. Women with frank and complete breech presentations (fetal weight <4000 g) encounter minimal problems, while those with footling breech are advised elective CS because of the increased risk of cord prolapse. CT or X‐ray pelvimetry do not appear to improve outcome. Spontaneous onset of labour is preferred and labour management is similar to vertex presentation. Successful outcome depends on a normal rate of cervical dilatation, descent of the breech and a normal fetal heart rate (FHR) pattern. Where progress of labour is poor and uterine contractions are inadequate, oxytocin augmentation can be used juidiciously with early resort to emergency CS if progress remains slow (<0.5 cm/hour), particularly in the late first stage. Epidural anaesthesia prevents bearing down before the cervix is fully dilated and is particularly important for labour with a preterm breech, when there is a real risk of head entrapment in the incompletely dilated cervix if pushing commences too early. For all breech labours, the mother should be encouraged to avoid bearing down for as long as possible. It is best to wait until the anterior buttock and anus of the baby are in view over the mother’s perineum, with no retraction between contractions. Classically, the mother’s legs are supported in the lithotomy position (the alternative upright breech technique is described later). Primigravidae will usually require an episiotomy with appropriate analgesia, although multigravidae can be assessed as the perineum stretches up. The buttocks deliver in the sacro‐tranverse position. The mother should be encouraged to push with contractions, aiming for an unassisted delivery up to and beyond the level of the umbilicus. There is no need to pull down a loop of cord. The accoucheur should sit with hands ready, but resting on their own legs. Assistance is only required if the legs do not deliver. Gentle abduction of the fetal thigh whilst hyperflexing the hip, followed by flexing the lower leg at the knee will release the foot and leg ( Fig. 26.4 ). Fig. 26.4 Delivery of extended legs by gentle abduction of the thigh with hyperflexion at the hip, followed by flexion at the knee: (a) right leg; (b) left leg. When the scapulae are visible with the arms flexed in front of the chest, sweep each arm around the side of the fetal chest to deliver using a finger placed along the length of the humerus. If the scapulae are not easily seen or if the arms are not easily reached, they may be extended above the shoulders. This can be resolved using the Løvset manoeuvre. Hold the baby by wrapping both hands around the bony pelvis, taking care not to apply pressure to the soft fetal abdomen. Rotate the baby 180° to bring the posterior shoulder to the front, i.e. to lie anteriorly ( Fig. 26.5 a). Complete delivery of the anterior arm by gently flexing the baby laterally downwards towards the floor; the arm will deliver easily from under the pubic ramus ( Fig. 26.5 b). Repeat the 180° rotation in the opposite direction, bringing the posterior shoulder to the front, then flex the baby laterally downwards to deliver the second arm. Fig. 26.5 Løvset’s manoeuvre for extended arms: (a) rotation to bring the posterior (left) arm to the front followed by (b) delivery of the left arm (now anterior) from under the pubic ramus. Nuchal displacement (an arm trapped behind the fetal neck) is rare. If the left arm is trapped, the baby will need to be rotated in a clockwise direction to ‘unwrap’ the arm so that it can be reached. If the right arm is involved, anticlockwise rotation is needed. Allow the head to descend into the pelvis, assisted by the weight of the fetus until the nape of the neck is visible under the symphysis pubis. Ensure slow controlled delivery of the head using one of four methods. Mauriceau–Smellie–Veit manoeuvre: two fingers are placed on the maxilla, lying the baby along the forearm. Hook index and fourth fingers of the other hand over the shoulders with the middle finger on the occiput to aid flexion. Apply traction to the shoulders with an assistant applying suprapubic pressure if needed ( Fig. 26.6 ). Burns–Marshall method: grasp the feet, apply gentle traction and swing the baby gently up and over the maternal abdomen until the mouth and nose appear. Forceps are applied to the head from below, with an assistant supporting the baby’s body in the horizontal plane avoiding hyperextension. Kielland’s forceps can be useful as they lack a pelvic curve. Apply traction, bringing the forceps upwards as the mouth and nose appear. The upright breech technique is increasingly popular in midwifery deliveries. Mobility is encouraged with delivery on all fours, sitting (on a birth stool), kneeling, standing or lying in a lateral position. Delivery is spontaneous with no manual assistance in 70% of cases and a reduced incidence of perineal trauma (14.9%). Fig. 26.6 Delivery of the head using the Mauriceau–Smellie–Veit manoeuvre assisted by suprapubic pressure. Entrapment of the aftercoming head This rare complication occurs in two situations. If the fetal back is allowed to rotate posteriorly, the chin may be trapped behind the symphysis pubis. Correction requires difficult internal manipulation to free the chin by pushing it laterally. McRoberts’ manoeuvre and suprapubic pressure may help. Symphysiotomy is a last resort that can increase the available pelvic diameters. In preterm delivery, the body can slip through an incompletely dilated cervix, with resulting head entrapment. If the cervix cannot be ‘stretched up’ digitally, surgical incisions are made in the cervical ring at 2, 6 and 10 o’clock (Dührssen incisions). Head entrapment in the contractile upper segment can occur at CS. Acute tocolysis and/or extension of the uterine incision may be required to release the head. Women should be intimately involved in decisions about mode of breech delivery and the available evidence presented appropriately. A senior midwife or a doctor experienced in assisted breech delivery must be present. As vaginal breech deliveries decline, developing expertise in breech delivery now relies on simulation training and experience of breech delivery at CS. Summary box 26.1 ECV has a high success rate (51–66%) and should be encouraged. Ensure the fetal back does not rotate posteriorly during breech delivery. The most experienced accoucheur available should directly supervise vaginal breech delivery. Brow presentation Brow presentation occurs in 1 in 1500–3000 deliveries. The head is partially deflexed (extended), with the largest diameter of the head presenting (mento‐vertical, 13.5 cm). The forehead is the lowest presenting part but diagnosis relies on identifying the prominent orbital ridges lying laterally. The eyeballs and nasal bridge may just be palpated lateral to the orbital ridges. Position is defined using the frontal bone as the denominator (i.e. ‘fronto‐‘). Persistent brow presentation results in true disproportion, but when diagnosed in early labour careful assessment of progress is appropriate. Flexion to vertex or further extension to face presentation occurs in 50% and vaginal delivery is possible. Cautious augmentation with oxytocin should only be considered in nulliparous patients for delay in the early active phase of labour. If brow presentation persists, emergency CS is recommended. Vaginal delivery of a brow presentation is possible in extreme prematurity. Preterm labour is best managed in the same way as term labour, with delivery by CS if progress slows or arrests. Cord prolapse is more common and, though rare, uterine rupture can occur in neglected labour or with injudicious use of oxytocin. For this reason labour should not be augmented in multigravid patients with a confirmed brow presentation if progress is inadequate. Face presentation Face presentation occurs in 1 in 500–800 labours. The general causes of malpresentation apply for face presentation, but fetal anomalies (neck or thyroid masses, hydrocephalus and anencephaly) should be excluded. The fetal head is hyperextended and the occiput may be felt higher and more prominently on the same side as the fetal spine. However, face presentation is rarely diagnosed antenatally. On vaginal examination in labour, diagnosis relies on feeling the mouth, malar bones, nose and orbital ridges. Position is defined using the chin or mentum as the denominator. The mouth and malar bones form a triangle which can help differentiate face presentation from breech, where the anus lies in a straight line between the prominent ischial tuberosities. Face presentation is often first diagnosed in late labour. The submento‐bregmatic diameter (9.5 cm) is compatible with normal delivery but only with the fetus in a mento‐anterior position (60%) ( Fig. 26.7 ). The same diameter presents with a persistent mento‐posterior position (25%) but this cannot deliver vaginally as the fetal neck is maximally extended. Fetal scalp clips, blood sampling and vacuum extraction are absolutely contraindicated. Forceps delivery from low cavity can be undertaken for mento‐anterior or mento‐lateral positions by an experienced accoucheur but CS may still be required when descent is poor. Fig. 26.7 The anteroposterior submento‐bregmatic diameter of face presentation. Shoulder presentation The incidence of shoulder presentation at term is 1 in 200 and is found with a transverse or oblique lie. Multiparity (uterine laxity) and prematurity are common associations and placenta praevia must be excluded. The lie will usually correct spontaneously before labour as uterine tone increases, although prolapse of the cord or arm is a significant risk if membranes rupture early. For this reason, hospital admission from 38 weeks is recommended for persistent transverse lie. External version can be offered (and may also be considered for transverse lie presenting in very early labour). On vaginal examination, the denominator is the acromium but defining position can be difficult. If membrane rupture occurs at term with the uterus actively contracting, delivery by CS should be undertaken promptly to avoid an impacted transverse lie. If the uterus is found to be moulded around the fetus, a classical CS is recommended to avoid both fetal and maternal trauma. In cases of intrauterine death with a transverse lie, spontaneous vaginal delivery is possible for early preterm fetuses by extreme flexion of the body (spontaneous evolution). However, CS will usually be required beyond mid‐trimester, although a lower segment approach may be used. Malposition and cephalopelvic disproportion In higher‐income countries, cephalopelvic disproportion is usually ‘relative’ and due to persistent malposition or relative fetal size (macrosomia). Classically we consider these problems with regard to the passage, the passenger or the powers, either alone or in combination. The passage Absolute disproportion due to a contracted pelvis is now rare in higher‐income countries unless caused by severe pelvic trauma and this should be known before the onset of labour. Caldwell and Moloy described four types of pelvis: gynaecoid (ovoid inlet, widest transversely, 50%), anthropoid (ovoid inlet, widest anteroposterior, 25%), android (heart‐shaped inlet, funnel‐shaped, 20%) and platypelloid (flattened gynaecoid, 3%). These can influence labour outcome but as pelvimetry is rarely used and clinical assessment of pelvic shape is inaccurate, this rarely influences clinical mangement in labour. The anthropoid pelvis is associated with a higher risk of persistent occipito‐posterior (OP) position and relative disproportion. The passenger and OP malposition Fetal anomalies (e.g. hydrocephalus, ascites) where disproportion may be a problem in labour are usually assessed antenatally and delivery by elective CS considered. Fetal macrosomia is increasing, related to the rising body mass index (BMI) in many pregnant populations. The evidence for inducing non‐diabetic women with an estimated fetal weight above the 90th centile (or >4000 g) in order to reduce cephalopelvic disproportion remains equivocal. Malposition is an increasingly common cause of disproportion and may be related to a sedentary lifestyle. OP position is associated with deflexion and/or asynclitism with a larger diameter presenting. Optimal uterine activity will correct the malposition in 75% of cases. Flexion occurs as the occiput reaches the pelvic floor with long rotation through 135° to an OA position and a high chance of normal delivery. Moulding of the fetal skull and pelvic elasticity (related to changes at the symphysis pubis) are dynamic changes that facilitate progress in labour and delivery. Short rotation through 45° to direct OP can result in spontaneous ‘face to pubes’ delivery, although episiotomy may be required to allow the occiput to deliver. Persistent OP position occurs in up to 25% of cases and is associated with further deflexion. The risk of assisted delivery is high because of relative disproportion as the presenting skull diameters increase. Delivery in the OP position from mid‐cavity (0 to +2 station) requires critical assessment to decide whether delivery should be attempted vaginally or abdominally and is discussed in later sections. The powers Disproportion is intimately related to dystocia and failure to progress in labour. National Institute for Health and Care Excellence (NICE) guidelines recommend that first stage delay is suspected with cervical dilatation of less than 2 cm in 4 hours when forewater amniotomy should be offered. Delay is confirmed if progress is less than 1 cm 2 hours later and oxytocin augmentation should be offered [6] . This shortens labour but does not affect operative delivery rates. High‐dose oxytocin may reduce CS rates but larger trials are required before these regimens are used routinely. The decision to use oxytocin in labour arrest in multigravid patients must only be made by the most senior obstetrician and should always be approached with extreme caution as uterine rupture is a possible consequence. In the second stage, particularly with epidural analgesia, passive descent for at least 1 hour is recommended, and possibly longer if the woman wishes, before encouraging active pushing. With regional analgesia and a normal FHR pattern, birth should occur within 4 hours of full dilatation regardless of parity [7] . Oxytocin may be commenced in nulliparous patients in the passive phase if contractions are felt to be inadequate and particularly with the persistent OP position. Failure of second‐stage descent combined with excessive caput or moulding suggests disproportion and requires critical assessment to decide the appropriate mode of delivery. Summary box 26.2 OP position with deflexion of the head and asynclitism results in relative disproportion compounded by inadequate uterine activity. With epidural analgesia in place, passive descent should be encouraged for at least 1 hour. Augmentation with oxytocin should be used with extreme caution in multigravid patients with labour arrest. Instrumental vaginal deliveries Background The incidence of instrumental vaginal delivery (IVD) varies widely and in Europe ranges from 0.5% (Romania) to 16.4% (Ireland), although there is no direct relationship with CS rates [ 8 , 9 ]. Epidural analgesia is associated with higher IVD rates. Allowing a longer passive second stage for descent results in less rotational deliveries and possibly a reduction in second‐stage CS [ 10 , 11 ]. Common indications for IVD include delay in the second stage of labour due to inadequate uterine activity, malposition with relative disproportion, maternal exhaustion and fetal compromise. Women with severe cardiac, respiratory or hypertensive disease or intracranial pathology may require IVD to shorten the second stage (when forceps may be preferred). Assessment and preparation for IVD The condition of the mother and fetus and the progress of labour should be assessed prior to performing IVD. Personal introductions to the woman and her partner are essential, explaining the reason for IVD and ensuring a chaperone and enough support are available. The findings, plan of action and the procedure itself should be explained and the discussions carefully recorded. Verbal or written consent is obtained. The mother and her partner may be physically and emotionally exhausted and great care should be exercised in terms of behaviour, communication and medical action. On abdominal examination, the fetal head should be no more than 1/5 palpable (preferably 0/5). A scaphoid shape to the lower abdomen may indicate an OP position. The FHR pattern should be assessed, noting any clinical signs of fetal compromise (e.g. fresh meconium). With acute fetal compromise (e.g. profound bradycardia, cord prolapse) delivery must be expedited urgently and this may only allow a brief explanation to be given to the patient and her partner at the time. If contractions are felt to be infrequent or short‐lasting, an oxytocin infusion should be considered in the absence of signs of fetal compromise. Both vacuum and forceps deliveries are associated with an almost threefold increased risk of shoulder dystocia compared with spontaneous delivery and this should be anticipated. However, it remains unclear whether this increased incidence is a cause or effect phenomenon [12] . On vaginal examination the cervix should be fully dilated with membranes absent. The colour and amount of amniotic fluid is recorded. Excessive caput or moulding may suggest the possibility of disproportion. Inability to reduce overlapping skull bones with gentle pressure is designated ‘moulding +++’; overlapping that reduces by gentle digital pressure is ‘moulding ++’, and meeting of the bones without overlap is ‘moulding +’. Identification of position, station, degree of deflexion and asynclitism will help decide whether IVD is appropriate, where it should be undertaken and who should undertake the procedure. Successful IVD is associated with station below the spines and progressive descent with pushing. If the head is 1/5 palpable abdominally, the leading bony part of the head is at the level of the ischial spines (mid‐cavity). When the head is more than 1/5 palpable and/or when station is above the spines, delivery by CS is recommended. Position is determined by identification of suture lines and fontanelles. The small posterior fontanelle (PF) lies at the Y‐shaped junction of the sagittal and lambdoidal sutures but may be difficult to feel when there is marked caput. The anterior fontanelle (AF) is a larger diamond‐shaped depression at the junction of the two parietal and two frontal bones. It can be differentiated from the PF by identifying the four sutures leading into the fontanelle. In deflexion (particularly OP positions) the AF lies centrally and is easily felt. Position can be confirmed by reaching for the pinna of the fetal ear, which can be flicked forwards indicating that the occiput lies in the opposite direction. Reaching the ear suggests descent below the mid‐pelvic strait. The degree of asynclitism should be assessed (see Fig. 26.1 ), with increasing degrees suggesting disproportion and a potentially more difficult IVD. Assessment of level and position can be difficult with OP position and in obesity. If there is any doubt after careful clinical examination, ultrasound assessment is recommended. The fetal orbits are sought and the position of the spine is noted. This is simple to do and can reduce the incorrect diagnosis of fetal position without delaying delivery, although on its own may not reduce morbidity associated with IVD [13] . IVD is normally performed with the mother in the dorsal semi‐upright position with legs flexed and abducted, supported by lithotomy poles or similar. The procedure is performed with good light and ideally aseptic conditions. The vulva and perineum should be cleansed and the bladder catheterized if the woman is unable to void. Adequate analgesia is essential and requires careful individualized assessment. Epidural anaesthesia is advisable for mid‐cavity IVD (i.e. station 0 to +2 cm below the ischial spines; see Fig. 26.2 ). In the absence of a pre‐existing epidural, spinal anaesthesia may be considered. IVD at station +2 cm or below is termed ‘low‐cavity’ and regional or pudendal block with local perineal infiltration (20 mL 1% plain lidocaine) can be used. Outlet IVD is performed when the head is on or near the perineum with the scalp visible without separating the labia. Descent to this level is associated with an OA position requiring minimal or no rotation and perineal infiltration with pudendal anaesthesia is effective. When the vertex is below the spines, IVD is carried out with different types of forceps or vacuum equipment, depending on the position and station of the vertex and the familiarity and experience of the doctor. Overall, comparing outcomes is easier if designation is by station and position at the time of instrumentation (e.g. left OP at +3) rather than simply mid, low or outlet IVD [ 11 , 14 ]. Choice of instruments: forceps or ventouse The choice of instrument depends on the operator’s experience, familiarity with the instrument, station and position of the vertex. Therefore, knowledge of the station and the position of the vertex is essential. The fetus in an OA position in the mid/low cavity can be delivered using non‐rotational, long or short‐handled forceps or a vacuum device: silicone, plastic or anterior metal cups (with suction tubing arising from the dorsum of the cup) are all suitable. For the fetus lying OT at mid‐ or low‐cavity, or lying OP position mid‐cavity, Kielland’s forceps or vacuum devices can be used to correct the malposition. Manual rotation is another technique to consider. Low‐cavity direct OP positions can be delivered ‘face to pubis’ but this may cause signifcant perineal trauma as the occiput delivers. For this reason, an OP vacuum cup (with the suction tubing arising from the edge of the cup) may be preferred. The cup will promote flexion and late rotation to OA often occurs on the perineum just prior to delivery. The Kiwi OmniCup® is an all‐purpose disposable vacuum delivery system with a plastic cup and in‐built PalmPump™ suitable for use in all positions of the vertex. Later models also display force traction to help the accoucheur avoid cup slippage ( http://clinicalinnovations.com/portfolio‐items/kiwi‐complete‐vacuum‐delivery‐system/ ) Forceps delivery Forceps come in pairs and most have fenestrated blades with a cephalic and pelvic curve between the heel and toe (distal end) of each blade. The heel continues as a shank which ends in the handle. The handles of the two blades sit together and meet at the lock. The cephalic curve fits along either side of the fetal head with the blades lying on the maxilla or malar eminences in the line of the mento‐vertical diameter ( Fig. 26.8 a). When correctly attached, uniform pressure is applied to the head, with the main traction force applied over the malar eminences. The shanks are over the flexion point, allowing effective traction in the correct direction. Non‐rotational forceps (the longer‐handled Neville Barnes or Simpson, and the shorter‐handled Wrigley’s) have a distinct pelvic curve that allows the blades to lie in the line of the pelvic axis whilst the handles remain horizontal. Kielland’s forceps have a minimal pelvic curve to allow rotation within the pelvis to correct malposition. Fig. 26.8 (a) Malar forceps application showing mento‐vertical diameter; (b) forceps traction (Pajot’s manoeuvre). Prior to applying forceps, the blades should be assembled to check whether they fit together as a pair. All forceps have matching numbers imprinted on the handles or shanks and these should also be checked. Non‐rotational forceps can be applied when the vertex is no more than 45° either side of the direct OA position (i.e. right OA to left OA). Application and delivery in a direct OP position is also possible but not routinely recommended because of increased perineal trauma. The left blade is inserted first using a light ‘pencil grip’, negotiating the pelvic and cephalic curves with a curved movement of the blade between the fetal head and the operator’s right hand, which is kept along the left vaginal wall for protection. Hands are swapped to insert the right blade using the same technique. Correct application results in the handles lying horizontally, right on top of left, and locking should be easy. Before applying traction, correct application must be confirmed: (i) the sagittal suture is lying midline, equidistant from and parallel to the blades; (ii) the occiput is no more than 2–3 cm above the level of the shanks (i.e. head well‐flexed); and (iii) no more than a fingertip passes into the fenestration at the heel of the blade. From mid‐ and low‐cavity, Pajot’s maneouvre should be used, balancing outward traction with one hand with downward pressure on the shanks with the other ( Fig. 26.8 b, white arrow). The handles are kept horizontal to avoid trauma to the anterior vaginal wall from the toes of the blades. Traction is synchronized with contractions and maternal effort, and the resultant movement is outwards down the line of the pelvic axis until the head is crowning. An episiotomy is usually needed as the perineum stretches up. The direction of traction is now upwards once the biparietal eminences emerge under the pubic arch and the head is born by extension. The mother will usually ask to have her baby handed to her immediately (unless active resuscitation is required). After completing the third stage, any perineal trauma is repaired and a full surgical count completed. The procedure, including plans for analgesia and bladder care, should be fully documented. Rotational forceps Kielland’s forceps have a minimal pelvic curve allowing rotation of the head at mid‐cavity. They are powerful forceps requiring a skilled accoucheur who is willing to abandon the procedure if progress is not as expected. The number of units able to teach use of Kielland’s forceps to the point of independent practice is declining in the UK. The forceps should match and are applied so that the knobs on the handles face the fetal occiput. Kielland’s are used to correct both OT and OP positions using two methods of application. Direct application involves sliding each blade along the side of the head if space permits, and is more easily achieved with OP positions. Wandering application is useful in OT positions. The first blade is applied in front of the fetal face, from where it is gently ‘wandered’ around to lie in the usual position alongside the malar bone. The posterior blade is applied directly using the space in the pelvic sacral curve. If application is difficult or the blades do not easily lock, the procedure should be abandoned. Correct application should be confirmed. Once locked, it is essential to hold the handles at a relatively steep angle downwards in the line of the mid‐pelvic axis in order to achieve easy rotation. Asynclitism is corrected using the sliding lock, moving the shanks over each other until the knobs are aligned. Rotation should take place between contractions, using only gentle force. Rotation may require the fetal head to be gently disimpacted, either upwards or downwards but no more than 1‐cm displacement is needed. Correct application should be checked again after rotation. Traction should result in progressive descent and an episiotomy is usually required. At the point of delivery, the handles of Kielland’s are only just above the horizontal because of the lack of pelvic curve. If there is no descent with traction during three contractions with maternal effort, the procedure should be abandoned. Whether Kielland’s delivery takes place in the delivery room or in obstetric theatre requires careful assessment of fetal and maternal condition, analgesia and labour progress. If there is any doubt, a formal trial of forceps should be arranged. Vacuum delivery Ventouse or vacuum delivery is increasingly favoured over forceps delivery for similar indications in the second stage of labour. The prerequisites to be satisfied before vacuum delivery are the same as for all forms of IVD. Vacuum delivery is contraindicated below 34 +0 weeks and should be used with caution between 34 +0 to 36 +0 weeks [11] . Overall it is contraindicated for fetuses with possible haemorrhagic tendencies (risk of subgaleal haemorrhage) and before full dilatation [11] . Experienced practitioners may consider vacuum after 8 cm in a multigravid patient in some circumstances. There are many types of vacuum cup in regular use, made of different materials and of differing shapes. Whichever cup is used, the aim is to ensure that the centre of the cup is directly over the flexion point. The flexion point is 3 cm in front of the occiput in the midline and is the point where the mento‐vertical diameter exits the fetal skull [15] . Traction on this point promotes flexion, presenting the smallest diameters for descent through the pelvis: this is the optimum flexing median application ( Fig. 26.9 a). Other applications increase the risk of cup detachment, failed vacuum delivery and scalp trauma. In decreasing order of effectiveness, these are the flexing paramedian application ( Fig. 26.9 b), the deflexing median application ( Fig. 26.9 c) and the deflexing paramedian application ( Fig. 26.9 d). Fig. 26.9 Placement of the vacuum cup, from most favourable (a) to unfavourable (d). (a) Flexing median; (b) flexing paramedian; (c) deflexing median; (d) deflexing paramedian. It is vitally important to select the correct cup and this will vary depending on both the position and attitude of the fetus. The soft Silc, Silastic or anterior metal cups (where the tubing is attached on the dorsum of the cup) are not suitable for OT or OP positions, as their shape and configuration do not allow application over the flexion point. They are suitable for OA positions where the flexion point is accessible in the midline. Metal cups come in different sizes, usually 4, 5 or 6 cm in diameter. In a systematic review they were more likely to result in successful vaginal birth than soft cups (RR 1.63, 95% CI 1.17–2.28), but with more cases of scalp injury (RR 0.67, 95% CI 0.53–0.86) and cephalhaematoma (RR 0.61, 95% CI 0.39–0.95) [16] . A specially designed cup should be used for OT and OP positions: metal OP cups have tubing emerging from the lateral aspect of the cup and the Kiwi OmniCup has a groove in the dorsum of the cup to accommodate the flexible stem. These cups can be manoeuvred more laterally or posteriorly to reach the flexion point. Hand‐held vacuum is associated with more failures than metal ventouse [16] , although a larger study suggested that the OmniCup has an overall failure rate of 12.9% [11] . Aldo Vacca (1941–2014) was the doyen of vacuum delivery and (with reference to the flexion point and cup application) his favourite quote was ‘It’s always more posterior than you think’. After ensuring flexion point application, the cup must be held firmly on the fetal scalp, and a finger should be run around the rim to ensure that no maternal tissue is entrapped. A vacuum of 0.2 bar (150 mmHg or 0.2 kg/cm 2 negative pressure) is created using a hand‐held or mechanical pump, before rechecking the position over the flexion point and confirming maternal tissue is not trapped. The vacuum is increased to 0.7–0.8 bar (500–600 mmHg or 0.8 kg/cm 2 ) in one step, waiting 2 min where possible to develop the ‘chignon’ within the cup. Axial traction in the line of the pelvic axis should be timed with uterine contractions and maternal pushing. A thumb should be placed on the cup, with the index finger on the scalp at the edge of the cup allowing the operator to feel any potential detachment before it is heard (by which point it is often too late to prevent detachment). Descent promotes auto‐rotation of the head to the OA position and episiotomy is often not required. Parents should be reassured that the ‘chignon’ will settle over 2–3 days. Manual rotation Manual rotation for persistent OP position is an alternative to IVD. The procedure requires insertion of one hand into the posterior vagina to encourage flexion and rotation. Careful patient selection is essential and the operator must ensure that effective analgesia is in place. The right hand is inserted for a left OP position (insert left hand for right OP). Four fingers are placed behind the fetal occiput to act as the ‘gutter’ on which the head will rotate, with the thumb placed alongside the anterior fontanelle. When the mother pushes with a contraction, the thumb applies pressure to flex the head and rotation to an OA position should occur with minimal effort. In a series ( N  = 61) where OP position was managed in two groups, the spontaneous delivery rate increased from 27% to 77% in the group offered digital rotation ( P <0.0001) [17] . Complications of IVD In a Cochrane review of 32 studies ( N  = 6597), forceps were less likely to fail to achieve a vaginal birth compared with ventouse (RR 0.65, 95% CI 0.45–0.94) [16] . Vaginal and perineal lacerations, including third‐ and fourth‐degree tears, are more common with forceps than with vacuum. Infra‐levator haematomas may occur occasionally and these should be drained if large or symptomatic. The risk of flatus incontinence or altered continence is also higher. Follow‐up of women who have had low or outlet IVD confirms normal physical and neourological outcomes for the vast majority of the newborn. In terms of neonatal outcome, cephalhaematoma is more common with vacuum but risk of facial injury is less. Facial and scalp abrasions are usually minor and heal in a few days. Unilateral facial nerve palsy is rare and resolves within days or weeks and is not usually related to poor technique. Skull fracture is rare and most need no treatment unless depressed, when surgical elevation may be indicated. Vacuum delivery may result in retinal haemorrhages, haematoma confined to one of the skull bones and neonatal jaundice. Severe scalp lacerations imply poor technique and are fortunately rare. Subgaleal haemorrhage may cause minor or severe morbidity and rarely mortality [18] . In reviewing morbidity associated with IVD, it is important to remember that the alternative option of second‐stage CS is also associated with increased morbidity for both mother and baby. Safe practice: sequential intrumentation and trial of instrumental delivery For all IVDs, the procedure should be abandoned if there is ‘no evidence of progressive descent with moderate traction during each contraction, or where delivery is not imminent following three contractions of a correctly applied instrument by an experienced operator’ [11] . Sequential instrumentation is associated with increased neonatal morbidity and the decision to proceed must take into account the relative risks of delivery by second‐stage CS from deep in the pelvis. It can be difficult to judge whether to proceed with IVD, especially in cases with mid‐cavity malposition at the level of the ischial spines. In such cases a trial of instrumental delivery should be undertaken in theatre under regional anaesthesia, with the full theatre team and neonatal practitioner present. The estimated incidence of trial of instrumental delivery is 2–5%. It is vital to maintain awareness of the situation, with a clear willingness to abandon the attempt if progress is not as expected, proceeding immediately to CS. The couple should be advised of this strategy and appropriate consent obtained prior to the procedure, which should be undertaken by the most senior obstetrician available. In the presence of fetal compromise, it is prudent to consider delivery by emergency CS, rather than proceeding with a potentially difficult IVD. Paired cord blood samples should be taken and results recorded after every attempted IVD. Contemporary developments in IVD New methods are being developed to achieve IVD and include disposable plastic forceps with the ability to measure traction force (see http://www.medipex.co.uk/success‐stories/pro‐nata‐yorkshire‐obstetric‐forceps/ and Fig. 26.10 ) and the Odon device where traction is applied using a plastic bag placed around the fetal head and neck. This device is undergoing trials led by the World Health Organization (see http://www.who.int/reproductivehealth/topics/maternal_perinatal/odon_device/en/ ). Fig. 26.10 Pro‐Nata Yorkshire obstetric forceps. Reproduced with permission of Mark Jessup.

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Vertex Position: What It Is, Why It's Important, and How to Get There

Jamie Grill / Getty Images

What Is the Vertex Position?

• Why It's Important

When the Vertex Position Usually Occurs

• How to Get Baby in This Position

Options if Baby Is Not in the Vertex Position

While you are pregnant, you may hear your healthcare provider frequently refer to the position or presentation of your baby, particularly as you get closer to your due date . What they are referring to is which part of your baby is presenting first—or which part is at the lower end of your womb or the pelvic inlet.

Consequently, when they tell you that your baby's head is down, that likely means they are in the vertex position (or another cephalic position). This type of presentation is the most common presentation in the third trimester. Here is what you need to know about the vertex position including how you might get your baby into that position before you go into labor .

The vertex position is a medical term that means the fetus has its head down in the maternal pelvis and the occipital (back) portion of the fetal skull is in the lowest position or presenting, explains Jill Purdie, MD, an OB/GYN and medical director at Northside Women’s Specialists , which is part of Pediatrix Medical Group.

When a baby is in the vertex position, their head is in the down position in the pelvis in preparation for a vaginal birth, adds Shaghayegh DeNoble, MD, FACOG , a board-certified gynecologist and a fellowship-trained minimally invasive gynecologic surgeon. "More specifically, the fetus’s chin is tucked to the chest so that the back of the head is presenting first."

Why the Vertex Position Is Important

When it comes to labor and delivery, the vertex position is the ideal position for a vaginal delivery, especially if the baby is in the occiput anterior position—where the back of the baby's head is toward the front of the pregnant person's pelvis, says Dr. DeNoble.

"[This] is the best position for vaginal birth because it is associated with fewer Cesarean sections , faster births, and less painful births," she says. "In this position, the fetus’s skull fits the birth canal best. In the occiput posterior position, the back of the fetus's head is toward the [pregnant person's] spine. This position is usually associated with longer labor and sometimes more painful birth."

Other fetal positions are sometimes less-than-ideal for labor and delivery. According to Dr. DeNoble, they can cause more prolonged labor, fetal distress, and interventions such as vacuum or forceps delivery and Cesarean delivery.

"Another important fact is that positions other than vertex present an increased risk of cord prolapse, which is when the umbilical cord falls into the vaginal canal ahead of the baby," she says. "For example, if the fetus is in the transverse position and the [pregnant person's] water breaks , there is an increased risk of the umbilical cord prolapsing through the cervix into the vaginal canal."

When it comes to your baby's positioning, obstetricians will look to see what part of the fetus is in position to present during vaginal birth. If your baby’s head is down during labor, they will look to see if the back of the head is facing your front or your back as well as whether the back of the head is presenting or rather face or brow, Dr. DeNoble explains.

"These determinations are important during labor, especially if there is consideration to the use of a vacuum or forceps," she says.

According to Dr. Purdie, healthcare providers will begin assessing the position of the baby as early as 32 to 34 weeks of pregnancy. About 75% to 80% of fetuses will be in the vertex presentation by 30 weeks and 96% to 97% by 37 weeks. Approximately 3% to 4% of fetuses will be in a non-cephalic position at term, she adds.

Typically, your provider will perform what is called Leopold maneuvers to determine the position of the baby. "Leopold maneuvers involve the doctor placing their hands on the gravid abdomen in several locations to find the fetal head and buttocks," Dr. Purdie explains.

If your baby is not in the vertex position, the next most common position would be breech, she says. This means that your baby's legs or buttocks are presenting first and the head is up toward the rib cage.

"The fetus may also be transverse," Dr. Purdie says. "The transverse position means the fetus is sideways within the uterus and no part is presenting in the maternal pelvis. In other words, the head is either on the left or right side of the uterus and the fetus goes straight across to the opposite side."

There is even a chance that your baby will be in an oblique position. This means they are at a diagonal within the uterus, Dr. Purdie says. "In this position, either the head or the buttocks can be down, but they are not in the maternal pelvis and instead off to the left or right side."

If your baby's head is not down, your provider will look to see if the buttocks are in the pelvis or one or two feet, Dr. DeNoble adds. "If the baby is laying horizontally, then the doctor needs to know if the back of the baby is facing downwards or upwards since at a Cesarean delivery it can be more difficult to deliver the baby when the back is down."

How to Get Baby Into the Vertex Position

One way you can help ensure that your baby gets into the vertex position is by staying active and walking, Dr. Purdie says. "Since the head is the heaviest part of the fetus, gravity may help move the head around to the lowest position."

If you already know that your baby is in a non-cephalic position and you are getting close to your delivery date, you also can try some techniques to encourage the baby to turn. For instance, Dr. Purdie suggests getting in the knee/chest position for 10 minutes per day. This has been shown to turn the baby around 60% to 70% of the time.

"In this technique, the mother gets on all fours, places her head down on her hands, and leaves her buttock higher than her head," she explains. "Again, we are trying to allow gravity to help us turn the fetus."

You also might consider visiting a chiropractor to try and help turn the fetus. "Most chiropractors will use the Webster technique to encourage the fetus into a cephalic presentation," Dr. Purdie adds.

There also are some home remedies, including using music, heat, ice, and incense to encourage the fetus to turn, she says. "These techniques do not have a lot of scientific data to support them, but they also are not harmful so can be tried without concern."

You also can try the pelvic tilt , where you lay on your back with your legs bent and your feet on the ground, suggests Dr. DeNoble. Then, you tilt your pelvis up into a bridge position and stay in this position for 10 minutes. She suggests doing this several times a day, ideally when your baby is most active.

"Another technique that has helped some women is to place headphones low down on the abdomen near the pubic bone to encourage the baby to turn toward the sound," Dr. DeNoble adds. "A cold bag of vegetables can be placed at the top of the uterus near the baby’s head and something warm over the lower part of the uterus to encourage the baby to turn toward the warmth. [And] acupuncture has also been used to help turn a baby into a vertex position."

If you are at term and your baby is not in the vertex position (or some type of cephalic presentation), you may want to discuss the option of an external cephalic version (ECV), suggests Dr. Purdie. This is a procedure done in the hospital where your healthcare provider will attempt to manually rotate your baby into the cephalic presentation.

"There are some risks associated with this and not every pregnant person is a candidate, so the details should be discussed with your physician," she says. "If despite interventions, the fetus remains in a non-cephalic position, most physicians will recommend a C-section for delivery."

Keep in mind that there are increased risks for your baby associated with a vaginal breech delivery. Current guidelines by the American College of Obstetricians and Gynecologists recommend a C-section in this situation, Dr. Purdie says.

"Once a pregnant person is in labor, it would be too late for the baby to get in cephalic presentation," she adds.

A Word From Verywell

If your baby is not yet in the vertex position, try not to worry too much. The majority of babies move into either the vertex position or another cephalic presentation before they are born. Until then, focus on staying active, getting plenty of rest, and taking care of yourself.

If you are concerned, talk to your provider about different options for getting your baby to move into the vertex position. They can let you know which tips and techniques might be right for your situation.

American College of Obstetrics and Gynecology. Obstetrics data definitions .

National Library of Medicine. Vaginal delivery .

Sayed Ahmed WA, Hamdy MA. Optimal management of umbilical cord prolapse .  Int J Womens Health . 2018;10:459-465. Published 2018 Aug 21. doi:10.2147/IJWH.S130879

Hjartardóttir H, Lund SH, Benediktsdóttir S, Geirsson RT, Eggebø TM. When does fetal head rotation occur in spontaneous labor at term: results of an ultrasound-based longitudinal study in nulliparous women .  Am J Obstet Gynecol . 2021;224(5):514.e1-514.e9. doi:10.1016/j.ajog.2020.10.054

Management of breech presentation: green-top guideline no. 20b .  BJOG: Int J Obstet Gy . 2017;124(7):e151-e177. doi:10.1111/1471-0528.14465

Kenfack B, Ateudjieu J, Ymele FF, Tebeu PM, Dohbit JS, Mbu RE. Does the advice to assume the knee-chest position at the 36th to 37th weeks of gestation reduce the incidence of breech presentation at delivery?   Clinics in Mother and Child Health . 2012;9:1-5. doi:10.4303/cmch/C120601

Cohain JS. Turning breech babies after 34 weeks: the if, how, & when of turning breech babies .  Midwifery Today Int Midwife . 2007;(83):18-65.

American College of Obstetrics and Gynecology. If your baby is breech .

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Labor and Birth Processes

Chapter 9 Labor and Birth Processes Deitra Leonard Lowdermilk Learning Objectives •  Explain five factors that affect the labor process. •  Describe the anatomic structure of the bony pelvis. •  Recognize the normal measurements of the diameters of the pelvic inlet, cavity, and outlet. •  Explain the significance of the size and position of the fetal head during labor and birth. •  Summarize the cardinal movements of the mechanism of labor for a vertex presentation. •  Identify the maternal anatomic and physiologic adaptations to labor. •  Describe fetal adaptations to labor. Key Terms and Definitions asynclitism Oblique presentation of the fetal head at the superior strait of the pelvis; the pelvic planes and those of the fetal head are not parallel attitude Relationship of fetal parts to each other in the uterus (e.g., all parts flexed or all parts flexed except neck extended) biparietal diameter Largest transverse diameter of the fetal head; measured between the parietal bones bloody show Vaginal discharge that originates in the cervix and consists of blood and mucus; increases as the cervix dilates during labor dilation Stretching of the external os from an opening a few millimeters in size to an opening large enough to allow the passage of the fetus effacement Thinning and shortening or obliteration of the cervix that occurs during late pregnancy or labor or both engagement In obstetrics, the entrance of the fetal presenting part into the superior pelvic strait and the beginning of the descent through the pelvic canal; usually the lowest part of the presenting part is at or below the level of ischial spines Ferguson reflex Reflex contractions (urge to push) of the uterus after stimulation of the cervix when the presenting part of the fetus reaches the perineal floor fontanels Broad areas, or soft spots, consisting of a strong band of connective tissue contiguous with cranial bones and located at the junctions of the bones lie Relationship existing between the long axis of the fetus and the long axis of the mother; in a longitudinal lie, the fetus is lying lengthwise or vertically, whereas in a transverse lie, the fetus is lying crosswise or horizontally in the uterus lightening Sensation of decreased abdominal distention produced by uterine descent into the pelvic cavity as the fetal presenting part settles into the pelvis; usually occurs 2 weeks before the onset of labor in nulliparas molding Overlapping of cranial bones or shaping of the fetal head to accommodate and conform to the bony and soft parts of the mother’s birth canal during labor position Relationship of a reference point on the presenting part of the fetus, such as the occiput, sacrum, chin, or scapula, to its location in the front, back, or sides of the maternal pelvis presentation That part of the fetus that first enters the pelvis and lies over the inlet; may be the head, face, breech, or shoulder presenting part That part of the fetus that lies closest to the internal os of the cervix station Relationship of the presenting fetal part to an imaginary line drawn between the ischial spines of the pelvis suboccipitobregmatic diameter Smallest anterior-posterior diameter of the fetal head; follows a line drawn from the middle of the anterior fontanel to the undersurface of the occipital bone Valsalva maneuver Forced expiratory effort against a closed airway, such as holding one’s breath and tightening the abdominal muscles (e.g., pushing during the second stage of labor) vertex Crown, or top, of the head Web Resources Additional related content can be found on the companion website at  http://evolve.elsevier.com/Lowdermilk/Maternity/ •  NCLEX Review Questions •  Assessment Videos: Fetal Lie, Presentation, Position •  Critical Thinking Exercise: Fetal Presentation D uring late pregnancy the woman and fetus prepare for the labor process. The fetus has grown and developed in preparation for extrauterine life. The woman has undergone various physiologic adaptations during pregnancy that prepare her for birth and motherhood. Labor and birth represent the end of pregnancy, the beginning of extrauterine life for the newborn, and a change in the lives of the family. This chapter discusses the factors affecting labor, the process involved, the normal progression of events, and the adaptations made by both the woman and the fetus. Factors Affecting Labor  At least five factors affect the process of labor and birth. These factors are easily remembered as the five P s: passenger (fetus and placenta), passageway (birth canal), powers (contractions), position of the mother, and psychologic response. The first four factors are presented here as the basis of understanding the physiologic process of labor. The fifth factor is discussed in Chapter 12 . Other factors that may be a part of the woman’s labor experience may be important as well. VandeVusse (1999) identified external forces that include place of birth, preparation, type of provider (especially nurses), and procedures. Physiologic response (sensations) was identified as an internal force. These factors are discussed generally in Chapter 12 because they relate to nursing care during labor. Further research investigating essential forces of labor is recommended. Passenger The way the passenger, or fetus, moves through the birth canal is determined by several interacting factors: the size of the fetal head, fetal presentation, fetal lie, fetal attitude, and fetal position. Because the placenta also must pass through the birth canal, it can be considered a passenger along with the fetus; however, the placenta rarely impedes the process of labor in a normal vaginal birth, except in cases of placenta previa. Size of the fetal head Because of its size and relative rigidity, the fetal head has a major effect on the birth process. The fetal skull is composed of two parietal bones, two temporal bones, the frontal bone, and the occipital bone ( Fig. 9-1, A ). These bones are united by membranous sutures: the sagittal, lambdoidal, coronal, and frontal ( Fig. 9-1, B ). Membrane-filled spaces called fontanels are located where the sutures intersect. During labor, after rupture of membranes, palpation of fontanels and sutures during vaginal examination reveals fetal presentation, position, and attitude. Fig. 9-1 Fetal head at term. A, Bones. B, Sutures and fontanels. The two most important fontanels are the anterior and posterior ones (see Fig. 9-1, B ). The larger of these, the anterior fontanel, is diamond shaped, is approximately 3 cm by 2 cm, and lies at the junction of the sagittal, coronal, and frontal sutures. It closes by 18 months after birth. The posterior fontanel lies at the junction of the sutures of the two parietal bones and the occipital bone, is triangular, and is approximately 1 cm by 2 cm. It closes 6 to 8 weeks after birth. Sutures and fontanels make the skull flexible to accommodate the infant brain, which continues to grow for some time after birth. Because the bones are not firmly united, however, slight overlapping of the bones, or molding of the shape of the head, occurs during labor. This capacity of the bones to slide over one another also permits adaptation to the various diameters of the maternal pelvis. Molding can be extensive, but the heads of most newborns assume their normal shape within 3 days after birth. Although the size of the fetal shoulders may affect passage, their position can be altered relatively easily during labor; thus one shoulder may occupy a lower level than the other. This position creates a shoulder diameter that is smaller than the skull, facilitating passage through the birth canal. The circumference of the fetal hips is usually small enough not to create problems.  Critical Thinking Exercise: Fetal Presentation Fetal presentation Presentation refers to the part of the fetus that enters the pelvic inlet first and leads through the birth canal during labor at term. The three main presentations are cephalic presentation (head first), occurring in 96% of births ( Fig. 9-2 ); breech presentation (buttocks or feet first), occurring in 3% of births ( Fig. 9-3, A-C ); and shoulder presentation, seen in 1% of births ( Fig. 9-3, D ). The presenting part is that part of the fetal body first felt by the examining finger during a vaginal examination. In a cephalic presentation the presenting part is usually the occiput, in a breech presentation it is the sacrum, and in the shoulder presentation it is the scapula. When the presenting part is the occiput, the presentation is noted as vertex (see Fig. 9-2 ). Factors that determine the presenting part include fetal lie, fetal attitude, and extension or flexion of the fetal head. Fig. 9-2 Examples of fetal vertex (occiput) presentations in relation to front, back, or side of maternal pelvis. Fig. 9-3 Fetal presentations. A-C, Breech (sacral) presentation. D, Shoulder presentation.  Assessment Video: Presentation Fetal Lie Lie is the relation of the long axis (spine) of the fetus to the long axis (spine) of the mother. The two primary lies are longitudinal, or vertical, in which the long axis of the fetus is parallel with the long axis of the mother (see Fig. 9-2 ); and transverse, horizontal, or oblique, in which the long axis of the fetus is at a right angle diagonal to the long axis of the mother (see Fig. 9-3, D ). Longitudinal lies are either cephalic or breech presentations, depending on the fetal structure that first enters the mother’s pelvis. Vaginal birth cannot occur when the fetus stays in a transverse lie. An oblique lie, one in which the long axis of the fetus is lying at an angle to the long axis of the mother, is uncommon and usually converts to a longitudinal or transverse lie during labor ( Cunningham, Bloom, Gilstrap, Leveno, Hauth, & Wenstrom, 2005 ).  Assessment Video: Fetal Lie Fetal Attitude Attitude is the relationship of the fetal body parts to each other. The fetus assumes a characteristic posture (attitude) in utero partly because of the mode of fetal growth and partly because of the way the fetus conforms to the shape of the uterine cavity. Normally the back of the fetus is rounded so that the chin is flexed on the chest, the thighs are flexed on the abdomen, and the legs are flexed at the knees. The arms are crossed over the thorax, and the umbilical cord lies between the arms and the legs. This attitude is termed general flexion (see Fig. 9-2 ).  Assessment Video: Position Deviations from the normal attitude may cause difficulties in childbirth. For example, in a cephalic presentation, the fetal head may be extended or flexed in a manner that presents a head diameter that exceeds the limits of the maternal pelvis, leading to prolonged labor, forceps- or vacuum-assisted birth, or cesarean birth. Certain critical diameters of the fetal head are usually measured. The biparietal diameter, which is approximately 9.25 cm at term, is the largest transverse diameter and an important indicator of fetal head size ( Fig. 9-4, B ). In a well-flexed cephalic presentation, the biparietal diameter will be the widest part of the head entering the pelvic inlet. Of the several anteroposterior diameters, the smallest and the most critical one is the suboccipitobregmatic diameter (approximately 9.5 cm at term). When the head is in complete flexion, this diameter allows the fetal head to pass through the true pelvis easily ( Fig. 9-4, A ; Fig. 9-5, A ). As the head is more extended, the anteroposterior diameter widens, and the head may not be able to enter the true pelvis (see Fig. 9-5, B, C ). Fig. 9-4 Diameters of the fetal head at term. A, Cephalic presentations: occiput, vertex, and sinciput; and cephalic diameters: suboccipitobregmatic, occipitofrontal, and occipitomental. B, Biparietal diameter. Fig. 9-5 Head entering pelvis. Biparietal diameter is indicated with shading (9.25 cm). A, Suboccipitobregmatic diameter: complete flexion of head on chest so that smallest diameter enters. B, Occipitofrontal diameter: moderate extension (military attitude) so that large diameter enters. C, Occipitomental diameter: marked extension (deflection) so that the largest diameter, which is too large to permit head to enter pelvis, is presenting. Fetal position The presentation or presenting part indicates the portion of the fetus that overlies the pelvic inlet. Position is the relationship of the presenting part (occiput, sacrum, mentum [chin], or sinciput [deflexed vertex]) to the four quadrants of the mother’s pelvis (see Fig. 9-2 ). Position is denoted by a three-letter abbreviation. The first letter of the abbreviation denotes the location of the presenting part in the right (R) or left (L) side of the mother’s pelvis. The middle letter stands for the specific presenting part of the fetus (O for occiput, S for sacrum, M for mentum [chin], and Sc for scapula [shoulder]). The third letter stands for the location of the presenting part in relation to the anterior (A), posterior (P), or transverse (T) portion of the maternal pelvis. For example, ROA means that the occiput is the presenting part and is located in the right anterior quadrant of the maternal pelvis (see Fig. 9-2 ). LSP means that the sacrum is the presenting part and is located in the left posterior quadrant of the maternal pelvis (see Fig. 9-3 ). Station is the relationship of the presenting part of the fetus to an imaginary line drawn between the maternal ischial spines and is a measure of the degree of descent of the presenting part of the fetus through the birth canal. The placement of the presenting part is measured in centimeters above or below the ischial spines ( Fig. 9-6 ). For example, when the lowermost portion of the presenting part is 1 cm above the spines, it is noted as being minus (−) 1. At the level of the spines, the station is said to be 0 (zero). When the presenting part is 1 cm below the spines, the station is said to be plus (+) 1. Birth is imminent when the presenting part is at +4 to +5 cm. The station of the presenting part should be determined when labor begins so that the rate of descent of the fetus during labor can be accurately determined. Fig. 9-6 Stations of presenting part, or degree of descent. The lowermost portion of the presenting part is at the level of the ischial spines, station 0. Engagement is the term used to indicate that the largest transverse diameter of the presenting part (usually the biparietal diameter) has passed through the maternal pelvic brim or inlet into the true pelvis and usually corresponds to station 0. Engagement often occurs in the weeks just before labor begins in nulliparas and may occur before labor or during labor in multiparas. Engagement can be determined by abdominal or vaginal examination. Passageway The passageway, or birth canal, is composed of the mother’s rigid bony pelvis and the soft tissues of the cervix, pelvic floor, vagina, and introitus (the external opening to the vagina). Although the soft tissues, particularly the muscular layers of the pelvic floor, contribute to vaginal birth of the fetus, the maternal pelvis plays a far greater role in the labor process because the fetus must successfully accommodate itself to this relatively rigid passageway. Therefore the size and shape of the pelvis need to be determined before labor begins. Bony pelvis The anatomy of the bony pelvis is described in Chapter 2 . The following discussion focuses on the importance of pelvic configurations as they relate to the labor process. (Referring to Fig. 2-4 may be helpful.) The bony pelvis is formed by the fusion of the ilium, ischium, pubis, and sacral bones. The four pelvic joints are the symphysis pubis, the right and left sacroiliac joints, and the sacrococcygeal joint ( Fig. 9-7, A ). The bony pelvis is separated by the brim, or inlet, into two parts: the false pelvis and the true pelvis. The false pelvis is the part above the brim and plays no part in childbearing. The true pelvis, the part involved in birth, is divided into three planes: the inlet, or brim; the midpelvis, or cavity; and the outlet. Fig. 9-7 Female pelvis. A, Pelvic brim above. B, Pelvic outlet from below. The pelvic inlet, which is the upper border of the true pelvis, is formed anteriorly by the upper margins of the pubic bone, laterally by the iliopectineal lines along the innominate bones, and posteriorly by the anterior, upper margin of the sacrum and the sacral promontory. The pelvic cavity, or midpelvis, is a curved passage with a short anterior wall and a much longer concave posterior wall. It is bounded by the posterior aspect of the symphysis pubis, the ischium, a portion of the ilium, the sacrum, and the coccyx. The pelvic outlet is the lower border of the true pelvis. Viewed from below, it is ovoid, somewhat diamond shaped, bounded by the pubic arch anteriorly, the ischial tuberosities laterally, and the tip of the coccyx posteriorly ( Fig. 9-7, B ). In the latter part of pregnancy, the coccyx is movable (unless it has been broken in a fall during skiing or skating, for example, and has fused to the sacrum during healing). The pelvic canal varies in size and shape at various levels. The diameters at the plane of the pelvic inlet, midpelvis, and outlet, plus the axis of the birth canal ( Fig. 9-8 ), determine whether vaginal birth is possible and the manner by which the fetus may pass down the birth canal. Fig. 9-8 Pelvic cavity. A, Inlet and midplane. Outlet not shown. B, Cavity of true pelvis. C, Note curve of sacrum and axis of birth canal. The subpubic angle, which determines the type of pubic arch, together with the length of the pubic rami and the intertuberous diameter, is of great importance. Because the fetus must first pass beneath the pubic arch, a narrow subpubic angle will be less accommodating than a rounded wide arch. The method of measurement of the subpubic arch is shown in Fig. 9-9 . A summary of obstetric measurements is given in Table 9-1 . TABLE 9-1 Obstetric Measurements PLANE DIAMETER MEASUREMENTS Inlet (superior strait)     Conjugate  Diagonal 12.5 to 13 cm (radiographic) Length of diagonal conjugate (blue line), obstetric conjugate (broken blue line), and true conjugate (white line) *  Obstetric: measurement that determines whether presenting part can engage or enter superior strait 1.5 to 2 cm less than diagonal  True (vera) (anteroposterior) ≥11 cm (12.5) (radiographic) Midplane     Transverse diameter (interspinous diameter) 10.5 cm Measurement of interspinous diameter * The midplane of the pelvis normally is its largest plane and the one of greatest diameter   Outlet     Transverse diameter (intertuberous diameter) (biischial) ≥8 cm Use of Thom’s pelvimeter to measure intertuberous diameter * The outlet presents the smallest plane of the pelvic canal  

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• Labor and Birth at Risk
• Transition to Parenthood
• Postpartum Complications
• Assessment and Care of the Newborn and Family

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Fetal Malpresentation and Malposition

Fetal presentation describes which part of the fetus will enter through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first, while position is the orientation Orientation Awareness of oneself in relation to time, place and person. Psychiatric Assessment of the fetus compared to the maternal bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 "hip" bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy . Presentations include vertex (the fetal occiput will present through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first), face, brow, shoulder, and breech. If a fetal limb is presenting next to the presenting part (e.g., the hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy is next to the head), this is known as a compound presentation. Malpresentation refers to any presentation other than vertex, with the most common being breech presentations. Vaginal delivery of a breech infant increases the risk for head entrapment and hypoxia Hypoxia Sub-optimal oxygen levels in the ambient air of living organisms. Ischemic Cell Damage , so, especially in the United States, mothers are generally offered a procedure to help manually rotate the baby to a head-down position instead (known as an external cephalic version) or a planned cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery .

Last updated: Feb 14, 2023

Fetal Lie and Presentation

Presenting diameter, management of cephalic and compound presentations, risks and management of breech and transverse presentations.

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• The “presenting part” refers to the part of the baby that will come through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first. 
• The position refers to how that body part (and thus the baby) is oriented within the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy . 
• The uterine fundus Fundus The superior portion of the body of the stomach above the level of the cardiac notch. Stomach: Anatomy is typically roomier, so babies tend to orient themselves head down so that their body and limbs occupy the larger portion of the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy .

Clinical relevance

• The maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy has a diameter of about 10 cm, through which the fetus must pass.
• The presentation and position of the fetus will determine how wide the fetus is (known as the “presenting fetal diameter”) as it attempts to pass through the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .
• Certain presentation/positions are more difficult (or even impossible) to pass through the pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy because of their large presenting diameter.
• Knowledge of the presentation and position are required to safely manage labor and delivery.

Risk factors for fetal malpresentation

• Multiparity (which can result in lax abdominal walls)
• Multiple gestations (e.g., twins)
• Prematurity Prematurity Neonatal Respiratory Distress Syndrome
• Uterine abnormalities (e.g., leiomyomas, uterine septa)
• Narrow pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy shapes
• Fetal anomalies (e.g., hydrocephalus Hydrocephalus Excessive accumulation of cerebrospinal fluid within the cranium which may be associated with dilation of cerebral ventricles, intracranial. Subarachnoid Hemorrhage )
• Placental anomalies (e.g.,   placenta previa Placenta Previa Abnormal placentation in which the placenta implants in the lower segment of the uterus (the zone of dilation) and may cover part or all of the opening of the cervix. It is often associated with serious antepartum bleeding and premature labor. Placental Abnormalities , in which the placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity covers the internal cervical os)
• Polyhydramnios Polyhydramnios Polyhydramnios is a pathological excess of amniotic fluid. Common causes of polyhydramnios include fetal anomalies, gestational diabetes, multiple gestations, and congenital infections. Patients are often asymptomatic but may present with dyspnea, extremity swelling, or abdominal distention. Polyhydramnios (too much fluid)
• Oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of Oligohydramnios (not enough fluid)
• Malpresentation in a previous pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care

Epidemiology

Prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency rates for different malpresentations at term:

• Vertex presentation, occiput posterior position: 1 in 19 deliveries
• Breech presentation: 1 in 33 deliveries
• Face presentation: 1 in 600–800 deliveries
• Transverse lie: 1 in 833 deliveries
• Compound presentation: 1 in 1500 deliveries 

Related videos

Fetal lie is how the long axis of the fetus is oriented in relation to the mother. Possible lies include:

• Longitudinal: fetus and mother have the same vertical axis (their spines are parallel).
• Transverse: fetal vertical axis is at a 90-degree angle to mother’s vertical axis (their spines are perpendicular).
• Oblique: fetal vertical axis is at a 45-degree angle to mother’s vertical axis (unstable, and will resolve to longitudinal or transverse during labor).

Presentation

Presentation describes which body part of the fetus will pass through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy first. Presentations include:

• Cephalic: head down
• Breech: bottom/feet down
• Transverse presentation: shoulder 
• Compound presentation: an extremity presents alongside the primary presenting part

Cephalic presentations

Cephalic presentations can be categorized as:

• Vertex presentation: chin Chin The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti). This line of fusion divides inferiorly to enclose a triangular area called the mental protuberance. On each side, inferior to the second premolar tooth, is the mental foramen for the passage of blood vessels and a nerve. Melasma flexed, with the occipital Occipital Part of the back and base of the cranium that encloses the foramen magnum. Skull: Anatomy fontanel as the presenting part
• Face presentation
• Brow presentation: forehead Forehead The part of the face above the eyes. Melasma is the presenting part

Vertex presentation

Face presentation (mentum anterior position)

Brow presentation (mentum posterior position)

Breech presentations

Breech presentations can be categorized as:

• Frank breech: bottom down, legs extended (50%–70%) 
• Complete breech: bottom down, hips and knees both flexed
• Incomplete breech: 1 or both hips not completely flexed
• Footling breech: feet down

Breech presentations: Frank (bottom down, legs extended), complete (bottom down, hips and knees both flexed), and footling (feet down) breech presentations

Transverse and compound presentations

• Uncommon, but when they occur, the presenting fetal part is the shoulder.
• If the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy begins dilating, the arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy may prolapse through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy .
• In compound presentations, the most common situation is a hand Hand The hand constitutes the distal part of the upper limb and provides the fine, precise movements needed in activities of daily living. It consists of 5 metacarpal bones and 14 phalanges, as well as numerous muscles innervated by the median and ulnar nerves. Hand: Anatomy or arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy presenting with the head.

Shoulder presentation (transverse lie)

Neglected shoulder presentation resulting in arm prolapse during labor

Vertex presentation with a compound hand

Fetal malpresentation

• Any presentation other than vertex
• Clinically, this means breech, face, brow, and shoulder presentations.

Position describes the relation of the fetal presenting part to the maternal bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .

Vertex positions

Positions for vertex presentations describe the position of the fetal occiput .

• Identified on cervical exam as the area in the midline between the anterior and posterior fontanelles Fontanelles Physical Examination of the Newborn
• Anterior, posterior, or transverse in relation to the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy
• Being on the maternal right or left
• Right or left occiput anterior
• Right or left occiput posterior
• Right or left occiput transverse
• Direct occiput anterior or posterior
• The most common positions (and easiest for vaginal delivery) are occiput anterior.

Overview of different vertex positions LOA: left occiput anterior LOP: left occiput posterior LOT: left occiput transverse OA occiput anterior OP: occiput posterior ROA: right occiput anterior ROP: right occiput posterior ROT: right occiput transverse

Face and brow positions

Positions for face and brow presentations describe the position of the chin Chin The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti). This line of fusion divides inferiorly to enclose a triangular area called the mental protuberance. On each side, inferior to the second premolar tooth, is the mental foramen for the passage of blood vessels and a nerve. Melasma .

• The chin Chin The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti). This line of fusion divides inferiorly to enclose a triangular area called the mental protuberance. On each side, inferior to the second premolar tooth, is the mental foramen for the passage of blood vessels and a nerve. Melasma is referred to as the mentum.
• Right or left mentum anterior
• Right or left mentum posterior
• Right or left mentum transverse
• Direct mentum anterior or posterior

Face presentation (mentum posterior position)

Breech and shoulder positions

• Positions for breech presentations describe the position of the sacrum Sacrum Five fused vertebrae forming a triangle-shaped structure at the back of the pelvis. It articulates superiorly with the lumbar vertebrae, inferiorly with the coccyx, and anteriorly with the ilium of the pelvis. The sacrum strengthens and stabilizes the pelvis. Vertebral Column: Anatomy . Similar to other presentations, they include anterior, posterior, and transverse and right, left, and direct.
• Dorso-superior (back up)
• Dorso-inferior (back down)

Dorso-inferior shoulder presentation

Dorso-superior shoulder presentation

Attitude and asynclitism

• Attitude: amount of flexion Flexion Examination of the Upper Limbs or extension Extension Examination of the Upper Limbs of the fetal head
• Lateral deflection of the sagittal Sagittal Computed Tomography (CT) suture to 1 side or the other
• Mild degrees of asynclitism are normal.
• More severe asynclitism increases the presenting fetal diameter and makes it more difficult for the fetal head to pass through the maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .

Fetal malposition

• Commonly refers to any position other than right occiput anterior, left occiput anterior, or direct occiput anterior
• All nonvertex presentations are also malpositioned.
• The terms fetal malpresentation and fetal malposition are often used interchangeably.
• The presenting diameter refers to the width of the presenting part.
• The maternal pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy is about 10 cm at its narrowest point; the infant must orient itself so that it can fit through.
• Most commonly, the infant will move into a cephalic, vertex presentation, in 1 of the occiput anterior positions → presents the narrowest diameter
• Vertex presentation: suboccipitobregmatic diameter, approximately 9.5 cm
• Vertex presentation with deflexed head: occipitofrontal diameter, approximately 11.5 cm
• Brow presentation: occipitomental diameter, approximately 13 cm
• Face presentation: submentobregmatic diameter, approximately 9.5 cm

Diameters of the fetal head

Comparison of presentation, attitude, and presenting diameter

How to establish lie, presentation, and position

Delivery is managed differently depending on the presentation and position of the infant. This information can be established in several different ways:

Leopold’s maneuvers

Ultrasonography.

• Cervical examination
• Techniques using abdominal palpation Abdominal Palpation Abdominal Examination to determine the presentation of the fetus
• The fetal head will be hard and round.
• The lower body will be bulkier, nodular, and mobile.
• The back will be hard and smooth.
• The other side (anterior surface of the fetus) will be filled with irregular, mobile fetal parts.
• Experienced providers can also estimate the fetal weight using these maneuvers.
• Bedside abdominal ultrasonography can easily identify the fetal head and its orientation Orientation Awareness of oneself in relation to time, place and person. Psychiatric Assessment .
• Quick bedside ultrasonography Bedside Ultrasonography ACES and RUSH: Resuscitation Ultrasound Protocols on admission to labor and delivery to assess fetal presentation is considered standard of care Standard of care The minimum acceptable patient care, based on statutes, court decisions, policies, or professional guidelines. Malpractice .
• The fetal head will typically encompass the entire window and appear like a large white circle (the fetal skull Skull The skull (cranium) is the skeletal structure of the head supporting the face and forming a protective cavity for the brain. The skull consists of 22 bones divided into the viscerocranium (facial skeleton) and the neurocranium. Skull: Anatomy ).
• Identification Identification Defense Mechanisms of the eyes can help determine position.
• It is quick and easy to perform and presents minimal risk to mother and infant.
• Allowing mothers to labor with infants in a noncephalic presentation significantly increases the risks to both of them.

Suprapubic bedside ultrasound showing the large white circle of the fetal skull, confirming a cephalic presentation F: fetal falx

Vaginal and cervical examination

• As the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy dilates, the fetal fontanelles Fontanelles Physical Examination of the Newborn can be directly palpated.
• Identifying the location of the fetal fontanelles Fontanelles Physical Examination of the Newborn allows the practitioner to establish the position.
• Insert 1–2 fingers through the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy posteriorly.
• Sweep fingers along the fetal head moving anteriorly.
• This maneuver allows for identification Identification Defense Mechanisms of the sagittal Sagittal Computed Tomography (CT) suture.
• The fontanelles Fontanelles Physical Examination of the Newborn are then identified by moving along the sagittal Sagittal Computed Tomography (CT) suture.

Vertex presentations

• Expectant management
• All have high chances of successful vaginal delivery.

Compound presentations

• Observation when labor is progressing normally (many compound presentations will resolve spontaneously intrapartum).
• Can attempt to gently pinch the compound extremity trying to provoke the fetus into withdrawing the part (no good quality Quality Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps. Quality Measurement and Improvement evidence, but unlikely to be harmful)
• Can attempt to manually replace the compound extremity
• If labor is prolonged and the compound part remains, cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery (CD) should be performed.
• Prolonged labor
• Umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity prolapse
• Increased maternal morbidity Morbidity The proportion of patients with a particular disease during a given year per given unit of population. Measures of Health Status from lacerations
• Ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage of the compound part

Brow presentations

• The majority spontaneously convert to a vertex presentation.
• Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery may be required if labor is prolonged.

Face presentations

• Management depends on the position.
• Can be delivered vaginally by an experienced provider
• Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery may be required.
• Head is fully extended and unable to pass through the birth canal Birth canal Pelvis: Anatomy .
• Normally, the fetal head flexes as it passes under the pubic bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types ; however, this is impossible in an MP position.
• Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery is always required (unless the infant spontaneously rotates to a mentum anterior (MA) position).

There are 3 primary options for managing breech presentations: performing CD, attempting an external cephalic version to manually rotate the baby into a vertex presentation for attempted vaginal delivery, or a planned vaginal breech delivery (which is generally not done in the United States).

Natural history of breech presentations

Most infants will spontaneously rotate to a vertex presentation as the pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care progresses. At different gestational ages, the prevalence Prevalence The total number of cases of a given disease in a specified population at a designated time. It is differentiated from incidence, which refers to the number of new cases in the population at a given time. Measures of Disease Frequency of breech presentations is:

• < 28 weeks: 20%–25%
• 32 weeks: 10%–15%
• Term (> 37 weeks): 3% 
• Spontaneous version is possible even at > 40 weeks.
• Flexed fetal legs
• Polyhydramnios Polyhydramnios Polyhydramnios is a pathological excess of amniotic fluid. Common causes of polyhydramnios include fetal anomalies, gestational diabetes, multiple gestations, and congenital infections. Patients are often asymptomatic but may present with dyspnea, extremity swelling, or abdominal distention. Polyhydramnios
• Longer umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity
• Lack of fetal/uterine anomalies
• Multiparity

Fetal risks associated with breech presentations

The following risks are associated with breech presentations in utero, regardless of mode of delivery:

• ↑ Association with congenital Congenital Chorioretinitis malformations
• Torticollis Torticollis A symptom, not a disease, of a twisted neck. In most instances, the head is tipped toward one side and the chin rotated toward the other. The involuntary muscle contractions in the neck region of patients with torticollis can be due to congenital defects, trauma, inflammation, tumors, and neurological or other factors. Cranial Nerve Palsies
• Developmental hip dysplasia 

Fetal risks associated with vaginal breech delivery

The primary risk of a vaginal breech delivery is fetal head entrapment:

• The fetal body delivers, but the head remains trapped in the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy .
• Causes compression Compression Blunt Chest Trauma of the umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity running past the head (between the delivered umbilicus and the undelivered placenta Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (chorionic villi) derived from trophoblasts and a maternal portion (decidua) derived from the uterine endometrium. The placenta produces an array of steroid, protein and peptide hormones (placental hormones). Placenta, Umbilical Cord, and Amniotic Cavity ) 
• Leads to hypoxia Hypoxia Sub-optimal oxygen levels in the ambient air of living organisms. Ischemic Cell Damage until head is delivered → ↑ risk of fetal death
• The cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy may not be fully dilated enough to accommodate the head.
• The fetal head may not fit through the bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy .
• The mother’s expulsive efforts are unable to quickly deliver the head.
• Umbilical cord Umbilical cord The flexible rope-like structure that connects a developing fetus to the placenta in mammals. The cord contains blood vessels which carry oxygen and nutrients from the mother to the fetus and waste products away from the fetus. Placenta, Umbilical Cord, and Amniotic Cavity prolapse during labor → requires emergent CD
• Birth injuries to the fetus (e.g., brachial plexus Brachial Plexus The large network of nerve fibers which distributes the innervation of the upper extremity. The brachial plexus extends from the neck into the axilla. In humans, the nerves of the plexus usually originate from the lower cervical and the first thoracic spinal cord segments (c5-c8 and T1), but variations are not uncommon. Peripheral Nerve Injuries in the Cervicothoracic Region injury)

Vaginal breech delivery

Vaginal breech deliveries for singleton gestations may be considered for certain low-risk women if vaginal delivery is strongly desired by the mother. In contrast, vaginal breech deliveries are done frequently for breech 2nd twins; the procedure is known as a breech extraction.

• Mothers must be fully counseled on risks.
• Mothers and infants should be monitored throughout labor with continuous electronic fetal heart rate Heart rate The number of times the heart ventricles contract per unit of time, usually per minute. Cardiac Physiology (FHR) and tocometry monitors.
• Mothers should understand that a CD will be recommended if there are signs of fetal distress or prolonged labor.
• Avoid artificial rupture of membranes to ↓ risk of cord prolapse.
• Frank or complete breech presentation with no hyperextension of the fetal head on ultrasonography
• No contraindications Contraindications A condition or factor associated with a recipient that makes the use of a drug, procedure, or physical agent improper or inadvisable. Contraindications may be absolute (life threatening) or relative (higher risk of complications in which benefits may outweigh risks). Noninvasive Ventilation to a vaginal birth
• No prior CDs
• Prior successful vaginal deliveries (i.e., multiparity)
• Gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care ≥ 36 weeks
• Spontaneous labor
• Normal bony pelvis Pelvis The pelvis consists of the bony pelvic girdle, the muscular and ligamentous pelvic floor, and the pelvic cavity, which contains viscera, vessels, and multiple nerves and muscles. The pelvic girdle, composed of 2 “hip” bones and the sacrum, is a ring-like bony structure of the axial skeleton that links the vertebral column with the lower extremities. Pelvis: Anatomy shown on X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests
• Estimated fetal weight Estimated Fetal Weight Obstetric Imaging between approximately 2500 and 3500 grams (exact range varies based on clinician Clinician A physician, nurse practitioner, physician assistant, or another health professional who is directly involved in patient care and has a professional relationship with patients. Clinician–Patient Relationship )
• Immediately after delivery of the 1st twin in the cephalic presentation, the physician reaches up into the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Uterus, Cervix, and Fallopian Tubes: Anatomy , manually grabs the infant’s legs, and gently guides them down through the birth canal Birth canal Pelvis: Anatomy while the cervix Cervix The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Externally, the cervix is lined by stratified squamous cells; however, the cervical canal is lined by columnar epithelium. Uterus, Cervix, and Fallopian Tubes: Anatomy is still fully dilated.
• ↓ Risk of head entrapment compared to singleton vaginal breech deliveries

External cephalic version

An external cephalic version (ECV) is a procedure in which the physician attempts to manually rotate the fetus from a breech to a cephalic presentation by pushing on the maternal abdomen.

• Approximately 50%–60% (higher in multiparous Multiparous A woman with prior deliveries Normal and Abnormal Labor than in nulliparous women) 
• 97% of infants remained cephalic at birth.
• 86% delivered vaginally.
• Women who are candidates for ECV should be counseled on their options to attempt an ECV, or they may simply elect to schedule a CD.
• Infant is full term in case emergent CD is required because of complications from the procedure (e.g., placental abruption Placental Abruption Premature separation of the normally implanted placenta from the uterus. Signs of varying degree of severity include uterine bleeding, uterine muscle hypertonia, and fetal distress or fetal death. Antepartum Hemorrhage ).
• Better ratio of infant size to fluid level than later in pregnancy Pregnancy The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth. Pregnancy: Diagnosis, Physiology, and Care
• Allows infant more time for spontaneous version than if the procedure was done earlier
• After a successful version, the mother can await spontaneous labor or be induced immediately, depending on the situation.
• There is still a chance that the infant may spontaneously rotate between the failed ECV and the planned CD date; therefore, presentation should always be checked immediately prior to CD.
• Another contraindication for a vaginal delivery (e.g., placenta previa Placenta Previa Abnormal placentation in which the placenta implants in the lower segment of the uterus (the zone of dilation) and may cover part or all of the opening of the cervix. It is often associated with serious antepartum bleeding and premature labor. Placental Abnormalities )
• Severe oligohydramnios Oligohydramnios Oligohydramnios refers to amniotic fluid volume less than expected for the current gestational age. Oligohydramnios is diagnosed by ultrasound and defined as an amniotic fluid index (AFI) of ‰¤ 5 cm or a single deep pocket (SDP) of Oligohydramnios
• Nonreassuring fetal monitoring Fetal monitoring The primary goals of antepartum testing and monitoring are to assess fetal well-being, identify treatable situations that may cause complications, and evaluate for chromosomal abnormalities. These tests are divided into screening tests (which include cell-free DNA testing, serum analyte testing, and nuchal translucency measurements), and diagnostic tests, which provide a definitive diagnosis of aneuploidy and include chorionic villus sampling (CVS) and amniocentesis. Antepartum Testing and Monitoring prior to the procedure
• A hyperextended fetal head
• Significant fetal or uterine anomalies
• Leads to fetal and maternal hemorrhage
• An immediate CD is required.
• If the version was successful, labor should be induced immediately.
• If the version was unsuccessful, the mother should undergo immediate CD.
• Cord prolapse: can occur with PROM PROM Prelabor rupture of membranes (PROM), previously known as premature rupture of membranes, refers to the rupture of the amniotic sac before the onset of labor. Prelabor rupture of membranes may occur in term or preterm pregnancies. Prelabor Rupture of Membranes and requires immediate/emergent CD.
• Common during the procedure, but typically resolves shortly after pressure on the abdomen is released.
• If distress persists, the mother should undergo an immediate CD.

Cesarean delivery Cesarean Delivery Cesarean delivery (CD) is the operative delivery of ≥ 1 infants through a surgical incision in the maternal abdomen and uterus. Cesarean deliveries may be indicated for a number of either maternal or fetal reasons, most commonly including fetal intolerance to labor, arrest of labor, a history of prior uterine surgery, fetal malpresentation, and placental abnormalities. Cesarean Delivery

• Scheduled at 39 weeks’ gestational age Gestational age The age of the conceptus, beginning from the time of fertilization. In clinical obstetrics, the gestational age is often estimated as the time from the last day of the last menstruation which is about 2 weeks before ovulation and fertilization. Pregnancy: Diagnosis, Physiology, and Care (WGA) if the infant is known to be in the breech presentation.
• Alternative option to attempting ECV
• Postpartum hemorrhage Postpartum hemorrhage Postpartum hemorrhage is one of the most common and deadly obstetric complications. Since 2017, postpartum hemorrhage has been defined as blood loss greater than 1,000 mL for both cesarean and vaginal deliveries, or excessive blood loss with signs of hemodynamic instability. Postpartum Hemorrhage
• Postpartum endomyometritis
• Maternal injury
• Longer recovery time postpartum
• Complications in future pregnancies (e.g., placenta previa Placenta Previa Abnormal placentation in which the placenta implants in the lower segment of the uterus (the zone of dilation) and may cover part or all of the opening of the cervix. It is often associated with serious antepartum bleeding and premature labor. Placental Abnormalities , placenta accreta Placenta Accreta Abnormal placentation in which all or parts of the placenta are attached directly to the myometrium due to a complete or partial absence of decidua. It is associated with postpartum hemorrhage because of the failure of placental separation. Placental Abnormalities , uterine rupture Uterine Rupture A complete separation or tear in the wall of the uterus with or without expulsion of the fetus. It may be due to injuries, multiple pregnancies, large fetus, previous scarring, or obstruction. Antepartum Hemorrhage )
• Maternal request (mother declines ECV attempt)
• ECV contraindicated
• ECV unsuccessful
• Fetal distress during labor

Management of transverse presentations

• As with breech presentations, mothers may be offered an attempt at ECV or a CD.
• Unlike breech presentations, vaginal transverse delivery is always contraindicated.
• Hofmeyr, G.J. (2021). Overview of breech presentation. In Barss, V.A. (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/overview-of-breech-presentation  
• Hofmeyr, G.J. (2021). Delivery of the singleton fetus in breech presentation. In Barss, V.A. (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/delivery-of-the-singleton-fetus-in-breech-presentation  
• Hofmeyr, G.J. (2021). External cephalic version. In Barss, V.A. (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/external-cephalic-version  
• Julien, S., and Galerneau, F. (2021). Face and brow presentations in labor. In Barss, V.A., (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/face-and-brow-presentations-in-labor  
• Strauss, R.A., Herrera, C.A. (2021). Transverse fetal lie. In Barss, V.A., (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/transverse-fetal-lie  
• Barth, W.H. (2021). Compound fetal presentation. In Barss, V.A., (Ed.), UpToDate. Retrieved July 14, 2021, from https://www.uptodate.com/contents/compound-fetal-presentation  
• Cunningham, F. G., Leveno, K. J., et al. (2010). Williams Obstetrics, 23rd ed., pp. 374‒382. 

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• Third Trimester
• Labor & Delivery

What Is Vertex Presentation?

Vertex presentation is just medical speak for “baby’s head-down in the birth canal and rearing to go!” About 97 percent of all deliveries are headfirst, or vertex—and rare is the OB who will try to deliver any other way.

Other, less common presentations include breech (when baby’s head is near your ribs) and transverse (which means the shoulder, arm or trunk is due to come out first because baby is lying on his side). Most babies will turn by about 34 weeks, but some have “unstable lies,” meaning they’re like a politician trying to make everyone happy—that is, they frequently flip positions.

About 95 percent of all babies will be head-down and ready to go by delivery day. If your little one isn’t vertex by 36 weeks, ask your doctor about your options. She may recommend doing a version procedure , in which the doctor tries to manually turn baby by pushing on your abdomen, but it does carry some risks and is only about 60 to 70 percent successful.

Expert: Melissa M. Goist, MD, assistant professor, obstetrics and gynecology, The Ohio State University Medical Center.

Please note: The Bump and the materials and information it contains are not intended to, and do not constitute, medical or other health advice or diagnosis and should not be used as such. You should always consult with a qualified physician or health professional about your specific circumstances.

Plus, more from The Bump:

Delivering a breech baby?

Shift breech baby before birth?

Will my baby be breech?

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Next on Your Reading List

Vertex Presentation: How does it affect your labor & delivery?

Medically Reviewed by: Dr. Veena Shinde (M.D, D.G.O,  PG – Assisted Reproductive Technology (ART) from Warick, UK) Mumbai, India

• >> Post Created: February 11, 2022
• >> Last Updated: April 5, 2024

Vertex Position - Table of Contents

As you approach the due date for your baby’s delivery, the excitement and apprehensions are at their peak! What probably adds to the anxieties are the medical terms describing the baby, its ‘position’ and ‘presentation.’ Let’s strike that out from the list now!

In simple words, ‘ position ’ of the baby is always in reference to the mother ; on what side of the mother’s pelvis does the baby lean more (left or right) and if the baby is facing the mother’s spine or belly (anterior or posterior) – for eg.: Left Occiput Anterior , Right Occiput Anterior , Right Occiput Posterior and so on.

On the other hand, ‘ presentation’ is the body part of baby (head, shoulder, feet, and buttocks) that will enter the mother’s pelvic region first at the beginning of labor.

As ‘ presentation’ depends on the ‘ position’ of the baby, the terms cannot be used interchangeably, which is often mistakenly done. If you are told by your doctor that your baby is in a head-down position , which means its head will enter the pelvic region first , then it means the baby is in ‘vertex’ presentation or even sometimes loosely referred to as vertex position of baby though its conceptually incorrect however it means the same.

With this article, we aim to explain how exactly vertex presentation affects your labor and delivery.

Understanding Vertex Presentation

If your baby is in the head-down position by the third trimester, then you are one of the 95% mothers who have a vertex baby or a vertex delivery. When the baby enters the birth canal head first, then the top part of the head is called the ‘vertex.’

In exact medical terms, we give you the definition of vertex presentation by the American College of Obstetrics and Gynecologists (ACOG) – “a fetal presentation where the head is presenting first in the pelvic inlet.”

Besides vertex presentation (also sometimes referred to as vertex position of baby or vertex fetal position also), the other occasional presentations (non-vertex presentations) include –

• Breech – baby’s feet or buttocks are down and first to enter the mother’s pelvic region. Head is near the mother’s ribs
• Transverse – baby’s shoulder, arm or even the trunk are the first to enter the pelvis, as the baby is laying on the side and not in a vertical position 

It is common that babies turn to a particular position (hence, affecting the presentation) by 34 -36 weeks of pregnancy. Nevertheless, some babies have ‘unstable lies’ ; – wherein the baby keeps changing positions towards the end of the pregnancy and not remaining in any one position for long.

Should you be worried if the baby is in vertex presentation?

Absolutely not! The vertex presentation is not only the most common, but also the best for a smooth delivery. In fact, the chances of a vaginal delivery are better if you have a vertex fetal position.

By 36 weeks into pregnancy, about 95% of the babies position themselves to have the vertex presentation. However, if your baby hasn’t come into the vertex fetal position by this time, then you can talk to your doctor about the options.

You may be suggested a cephalic version procedure   also known as the version procedure /external cephalic version (ECV procedure) – which is used to turn the baby/ fetus from a malpresentation – like breech, oblique or transverse (which occur just about 3-4% times) to the cephalic position (head down).

This is how your doctor will try to turn your baby manually by pushing on your belly to get the baby into the vertex presentation. But it is necessary for you to know that this procedure does involve some risk and is successful only 60-70% of the time.

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Risks of vertex position of baby: can there be any complications for the baby in the vertex presentation.

As discussed above, the vertex fetal position/presentation is the best for labor and delivery, but there can be some complications as the baby makes its way through the birth canal. One such complication can arise if the baby is on the larger side. The baby can face difficulty while passing through the birth canal even if it is in the head-down position because of the size.

Babies who weigh over 9 to 10 pounds are called ‘ macrosomic’ or even referred to as fetal macrosomia , and they are at a higher risk of getting their shoulders stuck in the birth canal during delivery, despite being in the head-down position.

In such cases, to avoid birth trauma for the baby, the American College of Obstetricians and Gynecologists (ACOG) suggests that cesarean deliveries should be limited to estimated fetal weights of at least 11 pounds in women without diabetes and about 9 pounds in women with diabetes.

In case of fetal macrosomia, your doctor will monitor your pregnancy more often and work out a particular birth plan for you subject to your age (mothers age) and size of your baby.

How will I deliver a baby in the vertex fetal position?

Even unborn human babies can astonish you if you observe the way they make their way through the birth canal during delivery.

A vertex baby may be in the optimal position ( head-down first in pelvis) for labor and delivery, but it does its own twisting and turning while passing through the birth canal to fit through. In humans, unlike other mammals, the ratio of the baby’s head to the space in the birth canal is quite limited.

The baby has to flex and turn its head in different positions to fit through and ultimately arrive in this world. And it does so successfully! It is a wonder how they know how to do this so naturally.

And to answer the question ‘how will I deliver a baby in the vertex position?’ – Simply NATURALLY i.e. vaginal delivery. Don’t worry, follow your doctor’s instructions, do your breathing and PUSH.

FAQs to keep ready: How can my doctor help me prepare as I approach my due date?

As your due date nears, apart from bodily discomfort, you may experience nervousness about the big day. Your doctor can help by clearing your doubts and putting you at ease. You can ask them the following questions to understand the process better.

Q1) How will I know if my baby is in vertex fetal position?

A doctor can confidently tell you whether or not your baby is in the vertex presentation. Many medical professionals will be able to determine your baby’s position merely by using their hands; this is called ‘Leopold’s maneuvers.’

However, in case they aren’t very confident about the baby’s position even after this, then an ultrasound can confirm the exact position of the baby.

You can also understand this through belly mapping . You are sure to feel the kicks towards the top of your stomach and head (distinct hard circular feel) towards your pelvis. 

Q2)Is there any risk of my vertex baby turning and changing positions?

Yes, in case of some women, the baby who has a vertex presentation may turn at the last moment.

What may cause this? Women who have extra amniotic fluid (polyhydramnios) have increased chances of a vertex baby turning into a breech baby at the last minute.

Discuss this with your doctor to understand what are the chances this might happen to you and what all you can do to keep the baby in the vertex presentation for delivery.

Q3) Is there need to be worried if my baby has a breech presentation?

Not really! There are loads of exercises which you which can help you get your baby in the right position.

Then there are the ECV (external cephalic version) procedure which can help in changing the position of your baby into the desired vertex position. Speak with your doctor.

Having a baby in breech position just before labor will require you to have a C-section . Let your doctor guide you. But there is nothing to worry about.

Q4) What may cause babies to come into breech position?

A few circumstances may cause the baby to come into breech position even after 36 weeks into pregnancy.

• If you are carrying twins or multiple babies , in which case there is limited space for each baby to move around.
• Low levels of amniotic fluid which restricts the free movement of the baby or even high levels of amniotic fluid that does not permit the baby to remain in any one position.
• If there are abnormalities in the uterus or other conditions like low-lying placenta or large fibroids in the lower part of the uterus.

Chances of breech babies are higher in births that are pre-term as the baby does not get enough time to flip into a head-down position – cephalic position – vertex presentation (vertex position of baby/ vertex fetal position).

Q5) Can a baby turn from breech position to vertex presentation?

Yes, a baby can turn from a breech position to vertex position / vertex fetal position over time with exercises and sometimes through ECV.

If an ultrasound has confirmed you have a breech baby, then you can do the following to turn it to a vertex baby. Try the following –

• Do not underestimate the wonders of daily walks of about 45-60 mins when it comes to bringing your baby in vertex presentation from breech presentation.
• Talk to your doctor about certain exercises that can help turn your baby in the head-down position. Exercises like ‘ high bridge’ or ‘cat and camel’ can help here. We recommend you to learn and try this only in the presence of a professional.
• External Cephalic Version (ECV ) is a way to manually maneuver the baby to vertex presentation. It is done with the help of an ultrasound and generally after 36 weeks into pregnancy. However, it has the success rate of just 50%. Discuss the risks, if any, with your gynecologist before opting for this procedure.

There are a couple of other unscientific methods that may not be safe to try –

• Light : Placing a torch near your vagina may guide the baby toward the light, and hence, get it in the vertex presentation.
• Music : Playing music near your belly’s bottom may urge the baby to move itself in the head-down position.

Q6) What all can I do to ensure I have a healthy delivery?

A healthy delivery requires the mother to be active, eating well, and staying happy. For any apprehensions regarding labor and delivery, do not hesitate to talk to your doctor and clarify your doubts.

Your doctor can help you understand your baby’s position and presentation, and then based on that they can plan your delivery to ensure your baby’s birth will happen in the safest possible way.

Try and maintain a healthy lifestyle which will also help in overall of your child and placenta health .

Key Takeaway

Yes, vertex presentation or vertex position of baby and vertex delivery are very common, normal, safe, and the best for labor and delivery of the baby. There is probability of complications sometimes, but that is only subject to certain conditions that we discussed above.

However, understand that any other baby position is also safe. The only thing with other positions and presentations is that the chances of a cesarean delivery goes up. Nevertheless, know what matters at the end of it all is a happy and healthy baby in your arms!

Happy pregnancy!

Khushboo Kirale

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Antenatal Care Module: 11. Assessing the Fetus

Study session 11  assessing the fetus, introduction.

In this study session, we turn our attention to the physical examination of the mother in order to find out about the position and health of her baby. You will learn how to examine the mother’s abdomen in order to determine whether the fetus is lying head up, head down, or sideways in her uterus. Listening to the fetal heartbeat can also give you information about the baby’s position and its wellbeing. At the end of the study session we guide you about what to do if you suspect that the baby’s position may lead to a difficult or dangerous birth, or if you suspect the woman may be having twins.

Learning Outcomes for Study Session 11

When you have studied this session, you should be able to:

11.1  Define and use correctly all of the key words printed in bold . (SAQ 11.1)

11.2  Know how to identify normal and abnormal lie of the fetus using palpation and auscultation. (SAQs 11.1 and 11.2)

11.3  Know how to assess fetal well-being by auscultation and fetal kick. (SAQs 11.1, 11.3 and 11.4)

11.4  Identify fetal conditions that require referral to the nearest health centre. (SAQ 11.4)

11.1  Finding the baby’s position in the uterus

The position of the baby in the uterus is known as the fetal lie . The purpose of finding the fetal lie is to identify whether there are any danger signs that could make labour and delivery difficult and put the mother and baby at risk.

Healthy signs

• There is only one baby in the uterus.
• The baby is head down at the time of birth.

Warning signs

• The baby is feet or bottom down at the time of birth.
• The baby is lying sideways at the time of birth.
• The mother has twins or triplets. You already know how to listen for two fetal heartbeats (Study Session 10).

There are two methods for finding the baby’s position — feeling the mother’s abdomen ( palpation ), and listening ( auscultation ) to where the fetal heartbeat is strongest. You may need to use both methods to be sure of the position of the baby.

Auscultation is pronounced ‘oss kool tay shun’.

11.2  Feeling the mother’s abdomen

It may be difficult to find the position of the baby before the sixth or seventh month of gestation, and it is not important until 36 weeks (eight months) because it is normal for the baby to move around until the final month. Once the pregnancy is at six or seven months, it will be easier to feel the baby and find its position in the uterus.

To begin, help the mother lie on her back and give her support under her knees and head. Make sure she is comfortable. The questions you are trying to answer when you examine her are:

• Is the baby vertical (up and down)? This is known as a vertical lie .
• Or is it lying sideways across her belly? This is a transverse lie .
• Is the baby facing the mother’s front, or her back?
• Is the baby head down ( cephalic presentation ) or bottom down (breech presentation )?

11.2.1  Is the baby vertical?

Most babies are lying vertically by the seventh month, with the baby’s head towards the cervix of the uterus. This is the safest position for a normal delivery. To find out if the baby is vertical, lay one hand flat on each side of the mother’s abdomen. Press in gently but firmly, first with one hand, and then with the other (Figure 11.1a). Check the shape carefully. Do the ends of the baby seem to be in the mother’s sides (Figure 11.1b)? If so, the baby is probably lying sideways. Many babies lie sideways in the first months, but most turn head down by eight months or so. Babies cannot be born through the vagina from the sideways position. A baby that is sideways and cannot be turned when labour starts must be born by caesarean surgery in a hospital.

It can be difficult to feel the position of the baby if the mother has very strong muscles on her abdomen, or if she has a lot of fat on her abdomen. If you have a hard time feeling the position, ask the mother to take a deep breath and let it out slowly, and to relax her body as you palpate (feel) her abdomen.

11.2.2  Is the baby facing the mother’s front, or her back?

Next, feel the mother’s abdomen for a large, hard shape (the baby’s back). If you can feel it (Figure 11.2a), the baby is facing the mother’s back. If you cannot feel the baby’s back, feel for a lot of small lumps (Figure 11.2b). If you feel a lot of small lumps instead of a large, hard shape, it probably means that you are feeling the baby’s arms and legs, which tell you that it is facing the mother’s front.

11.2.3  Is the baby head down or bottom down?

By the last month before birth, most babies are lying with their head towards the cervix of the uterus (Figure 11.3a). The head down position is called a cephalic presentation, and if the part of the fetal skull called the vertex comes down the birth canal first, it is the easiest presentation for childbirth. Doctors and midwives refer to the part of the baby that is pointing into the cervix of the uterus as the presenting part . In Figure 11.3a, the presenting part is the baby’s head, and in Figure 11.3b, the presenting part is the baby’s bottom. You will learn about other presentations (face, brow, shoulder) in the Module on Labour and Delivery Care .

Which part of the fetal skull is the vertex ? (Think back to Study Session 6. You may wish to look again at Figure 6.5, which shows the bones of the fetal skull.)

The vertex is the area of the fetal skull midway between the anterior fontanel (the space between the bones at the front of the baby’s head), and the posterior fontanel (the space between the bones at the back of the baby’s head).

11.2.4  Feeling for the baby’s head

By the seventh or eight month, the baby’s head has usually moved down in the mother’s pelvis. Here is how to feel for the baby’s head:

1  Find the mother’s pubic bone with your fingers. You can feel it just under the skin under the mother’s pubic hair (Figure 11.4).

2  As she breathes out, press deeply just above her pubic bone (see Figure 11.5). Be gentle and stop if you hurt her. If you feel a round, hard object that you can move a little from side to side, it is probably the back or side of the baby’s head.

If you do not feel anything in the mother’s lower belly, the baby may be lying sideways.

3  If the shape is not clearly round, it may be the baby’s face or the baby’s bottom that you can feel. Or sometimes the baby’s bottom is up, but the head is not straight down (Figure 11.6a and b). The head may be bent to the side, or the chin may be up (Figure 11.6c). These could be signs that the baby will not fit through the mother’s pelvis at birth.

4  If the lower part of the baby is not too deep in the mother’s pelvis, try moving that part of the baby from side to side, using gentle rocking movements with your hands on either side of the lower part of her abdomen (Figure 11.7). If moving the lower part of the baby makes its whole back move, then the baby may be breech. If the back does not move, then the baby may be head down.

5  Now feel the top of the mother’s uterus (the fundus), just below her ribs. Does it feel round and hard, like a head? Or is it a different shape — like a bottom, a back, or legs? If the top of the uterus feels more like a head than what you felt in the mother’s lower belly, the baby may be breech.

6  Put one hand on the baby’s back. At the same time, with your other hand, push the top end of the baby gently sideways (Figure 11.8). If the whole of the baby’s back moves when you move the top end, the baby is probably in the head-down position (Figure 11.8a). If the back stays where it is while you move the upper part of the baby (Figure 11.8b), you may be moving the head. This is because the neck can bend while the back stays in place. If you are moving the head at the top of the uterus, then the baby is breech.

7  When you check the baby’s position, you might think you feel two heads or two bottoms. The mother may have twins.

Think back to Study Session 10. What should you do if you suspect that a woman is having twins?

Refer the mother to a health centre immediately.

11.2.5  Asking the mother about the baby’s kicks

Doctors and midwives refer to fetal kick (not kicks) as an indicator of fetal wellbeing, and it may also indicate the fetal lie.

As you feel the mother’s abdomen, try to imagine the different positions the baby might be in. Imagine where the baby’s hands and legs might be. Imagine how each position would feel to the mother when the baby kicks. Then ask the mother where she feels the strongest kicks and where she feels smaller movements. Is this where you think the legs and hands probably are (see Figure 11.9)?

If the baby is healthy and getting adequate nutrients from the mother, it moves in the uterus in such a way that the woman feels it as a kick. Fetal kick is often clearly felt after the mother has eaten a meal, and when she has rested very well and is lying on her side.

If the woman tells you the baby is not moving as it used to, or is not moving at all, it could be sick or it may have died.

11.3  Listening for the baby’s heartbeat

The baby’s heartbeat gives information about the baby’s position inside the mother, and about the health of the baby. Listen to the heartbeat at each antenatal visit, starting at five months. Doctors and midwives often refer to the fetal heartbeat .

By the last two months of pregnancy, you can often hear the fetal heartbeat in a quiet room by putting your ear on the mother’s abdomen (Figure 11.10a). The heartbeat will be easier to hear if you have a stethoscope (Figure 11.10b) or a fetoscope (Figure 11.10c and d). If you don’t have a fetoscope, you can make a simple one from wood, clay, or a hollow tube of bamboo.

The fetal heartbeat is quiet and quick. It may sound like a watch ticking under a pillow, only faster. The fetal heartbeat is about twice as fast as a healthy adult heartbeat — usually 120 to 160 beats a minute. There is no need to count the heartbeats until the woman goes into labour. Hearing a clear fetal heartbeat during an antenatal visit just confirms that the baby is alive.

If you hear a ‘swishy’ sound (shee-oo, shee-oo, shee-oo), you are probably hearing the baby’s pulse in the umbilical cord. Cord sounds tell you how fast the baby’s heart is beating, but they do not help you find the baby’s position.

If the heartbeat sounds slow, you are probably hearing the mother’s pulse instead of the baby’s. Try listening to a different place on her abdomen.

11.3.1  Finding the baby’s position by listening to the heartbeat

Think about which way the baby seems to be lying. Then start listening for the heartbeat near the spot where you think the baby’s heart should be. You may need to listen in many places on the mother’s abdomen before you find the spot where the heartbeat is the most loud and clear (Figure 11.11).

Is the heartbeat loudest above or below the mother’s bellybutton? If you hear the heartbeat loudest below the mother’s bellybutton, the baby is probably head down (Figure 11.12a). If you hear the heartbeat loudest above the mother’s bellybutton, the baby may be in the breech position (Figure 11.12b).

Sometimes when the baby is facing the mother’s front, the heartbeat is harder to find because the baby’s arms and legs get in the way. Listen near the mother’s sides, or directly in the middle of her abdomen, to hear the fetal heartbeat.

11.4  What to do if you find warning signs

11.4.1  baby is breech.

Breech babies are often born without any trouble, especially if the mother has had other children and her births were easy. But breech babies are more likely to get stuck, or have other serious problems.

Box 11.1 Don’t try to turn a breech baby!

Only a midwife, health officer or physician who has been trained to turn a breech baby should try to do so, and it should be done in a hospital. Trying to turn the baby by pushing on the uterus is very dangerous. Even a midwife, health officer or physician should not try to turn a baby if the mother’s water has broken, or if she has had vaginal bleeding, high blood pressure, surgery on her uterus, or caesarean surgery.

If the baby is not head down when labour starts, it is safer for the mother to give birth in a hospital. The midwife, health officer or physician can use forceps (pulling tools) if the baby gets stuck. Or they can do a caesarean surgery.

11.4.2  Baby is lying sideways

Sideways babies cannot fit through the mother’s pelvis to be born (Figure 11.13). If you try to deliver the baby without surgery, the mother’s uterus will rupture during labour, and she and the baby will die without medical care. If the baby turns head down at any time — even on the day the mother goes into labour — it is OK for her to give birth at home or at the Health Post.

11.4.3  Twins

Think back to what you learned in Study Session 10 about twin pregnancy.

What are the three signs of twin pregnancy?

The uterus grows faster or larger than normal. You can feel two heads or two bottoms when you feel the mother’s belly. You can hear two heartbeats (this is not easy, but it may be possible in the last few months).

What are the two ways to try to hear the heartbeats of twins?

Find the heartbeat of one baby. Ask a helper to listen for other places where the heartbeat is easy to hear, and both of you tap the rhythm of the heartbeats.

Use a watch to help you count the two heartbeats.

11.5  After the antenatal check-up

After you have finished checking the fetus and the mother, and following the instructions for any warning signs, find out if the woman has any more questions, or needs to talk about anything else. If she has any warning signs, carefully explain what the warning sign is, and what she must do to care for herself. If this is a return antenatal check-up, evaluate what you did for her at the previous check-up. Decide what else you may need to do for her. If she needs to be referred to a higher-level health facility, be sure she knows where and when to go.

11.6  Conclusion

In this session, you have learned how to examine the abdomen of a pregnant woman so that you can determine the position of the baby, its presenting part (head or bottom, or whether it is lying sideways), and how to check the wellbeing of the fetus by listening to the fetal heartbeat and asking the mother about fetal kick.

Summary of Study Session 11

In Study Session 11, you have learned that:

• It is reassuring to find one baby in the uterus and that the head of the fetus is down in the last month of pregnancy. Most babies are lying vertically by the seventh month with their head towards the cervix of the uterus. By the seventh or eighth month, the baby’s head has usually moved down in the mother’s pelvis. This is the safest position for a normal delivery.
• In any other situation, i.e. the baby is bottom down (breech), or lying sideways (transverse), refer the mother to the nearest health facility. Do not attempt to turn a breech or transverse baby.
• The position in the mother’s abdomen where she can feel the baby kicking can help you determine its position. Fetal kick is also a sign of fetal health. If the baby stops kicking it may be sick or have died, and the mother needs urgent referral.
• The baby’s heartbeat gives information about the baby’s position inside the mother, and whether it is alive. Hearing two heartbeats is a sign of twins. Listen to the heartbeat at each antenatal visit, starting at five months.
• By the last two months of pregnancy, you can often hear the baby’s heartbeat in a quiet room by putting your ear on the mother’s belly. The heartbeat will be easier to hear if you have a stethoscope or a fetoscope.
• The normal fetal heart rate is usually about 120 to 160 beats per minute.

Self-Assessment Questions (SAQs) for Study Session 11

Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering these questions. Write your answers in your Study Diary and discuss them with your Tutor at the next Study Support Meeting. You can check your answers with the Notes on the Self-Assessment Questions at the end of this Module.

SAQ 11.1 (tests Learning Outcomes 11.1, 11.2 and 11.3)

Which of the following statements is false ? In each case, say why it is incorrect.

A  Listening to the fetal heartbeat using a stethoscope is called auscultation.

B  When the fetal head is down and the bottom of the fetus is up in the fundus, it is called a vertical lie.

C  In a vertex presentation, the presenting part is the baby’s bottom.

D  The fetal heart rate is normally 120 to 160 beats a minute.

E  If the fetal heartbeat sounds loudest below the mother’s bellybutton, the fetal lie is probably breech.

A  True. Listening to the fetal heart beat using a stethoscope is called auscultation.

B  True. When the fetal head is down and the bottom of the fetus is up in the fundus, it is called a vertical lie.

C   False . In a vertex presentation, the presenting part is the baby’s head.

D  True. The fetal heart rate is normally 120 to 160 beats a minute.

E   False . In a breech presentation, the fetal heartbeat sounds loudest above the mother’s bellybutton.

Read the following case study carefully, and then answer SAQs 11.2 to 11.4.

Case Study 11.1  Bekelech

Bekelech came for her antenatal check-up at the eighth month of pregnancy. When you palpated her abdomen, you found a hard, round mass in the fundus of the uterus, and a soft, irregular, bulky mass towards the symphysis pubic. Bekelech told you that in the past week the baby’s kick had decreased, and when you listened to her abdomen with a fetoscope you could not hear the fetal heartbeat.

SAQ 11.2 (tests Learning Outcome 11.2)

a. Is the fetal lie in Bekelech’s case vertical or transverse? Explain how you reached your conclusion.

b. What is the presenting part in this case?

c. What do you call a fetus presenting in such a manner?

a. The hard, round mass in the fundus of the uterus is most likely to be the baby’s back, and the soft irregular shapes towards the pubic symphysis are its arms and legs. This is a vertical lie.

b. The bottom is the presenting part.

c. This is called a breech presentation.

SAQ 11.3 (tests Learning Outcome 11.3)

Where would you listen to the fetal heartbeat to confirm your diagnosis of how Bekelech’s baby is presenting, and why?

You would listen for the fetal heartbeat above Bekelech’s bellybutton because, if the baby is breech, its heartbeat will sound loudest there. (Look again at Figure 11.12 if you are not sure why this is so.)

SAQ 11.4 (tests Learning Outcomes 11.3 and 11.4)

What do you suspect is the condition of Bekelech’s baby, and what action should you take?

The baby may be sick, or even dead, because Bekelech says it isn’t kicking and you can’t hear a fetal heartbeat. You should refer her to a health facility immediately.

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Delivery, Face and Brow Presentation

Affiliations.

• 1 Vilnius University, Lithuania, Imperial London Healthcare NHS Trust
• 2 University of Health Sciences, Rawalpindi Medical College
• PMID: 33620804
• Bookshelf ID: NBK567727

The term presentation describes the leading part of the fetus or the anatomical structure closest to the maternal pelvic inlet during labor. The presentation can roughly be divided into the following classifications: cephalic, breech, shoulder, and compound. Cephalic presentation is the most common and can be further subclassified as vertex, sinciput, brow, face, and chin. The most common presentation in term labor is the vertex, where the fetal neck is flexed to the chin, minimizing the head circumference.

Face presentation – an abnormal form of cephalic presentation where the presenting part is mentum. This typically occurs because of hyperextension of the neck and the occiput touching the fetal back. Incidence of face presentation is rare, accounting for approximately 1 in 600 of all presentations.

In brow presentation, the neck is not extended as much as in face presentation, and the leading part is the area between the anterior fontanelle and the orbital ridges. Brow presentation is considered the rarest of all malpresentation with a prevalence of 1 in 500 to 1 in 4000 deliveries.

Both face and brow presentations occur due to extension of the fetal neck instead of flexion; therefore, conditions that would lead to hyperextension or prevent flexion of the fetal neck can all contribute to face or brow presentation. These risk factors may be related to either the mother or the fetus. Maternal risk factors are preterm delivery, contracted maternal pelvis, platypelloid pelvis, multiparity, previous cesarean section, black race. Fetal risk factors include anencephaly, multiple loops of cord around the neck, masses of the neck, macrosomia, polyhydramnios.

These malpresentations are usually diagnosed during the second stage of labor when performing a digital examination. It is possible to palpate orbital ridges, nose, malar eminences, mentum, mouth, gums, and chin in face presentation. Based on the position of the chin, face presentation can be further divided into mentum anterior, posterior, or transverse. In brow presentation, anterior fontanelle and face can be palpated except for the mouth and the chin. Brow presentation can then be further described based on the position of the anterior fontanelle as frontal anterior, posterior, or transverse.

Diagnosing the exact presentation can be challenging, and face presentation may be misdiagnosed as frank breech. To avoid any confusion, a bedside ultrasound scan can be performed. The ultrasound imaging can show a reduced angle between the occiput and the spine or, the chin is separated from the chest. However, ultrasound does not provide much predicting value in the outcome of the labor.

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Traditional Obstetric Pelvimetry in Delivery and Labor

• First Online: 05 January 2021

Cite this chapter

• Fatima Estrada Trejo 2 ,
• Kfier Kuba 2 &
• Edith Gurewitsch Allen 2  

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In a time when decreasing the number of unnecesary surgeries is of great interest, understanding normal labor, dystocic labor, and when to intervine in order to improve the fetal and maternal outcome is of utmost importance. In the following chapter we describe the history of pelvimetry, the previously characterized types of pelvis and their application to childbirth.

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Maternal Fetal Medicine Division, Department of Obstetrics and Gynecology and Women’s Health, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, USA

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Estrada Trejo, F., Kuba, K., Gurewitsch Allen, E. (2021). Traditional Obstetric Pelvimetry in Delivery and Labor. In: Malvasi, A. (eds) Intrapartum Ultrasonography for Labor Management. Springer, Cham. https://doi.org/10.1007/978-3-030-57595-3_9

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