Overview of breech presentation

INTRODUCTION — Breech presentation, which occurs in approximately 3 percent of fetuses at term, describes the fetus whose presenting part is the buttocks and/or feet. Although most breech fetuses have normal anatomy, this presentation is associated with an increased risk for congenital malformations and mild deformations, torticollis, and developmental dysplasia of the hip. Pregnant people with fetuses in breech presentation at or near term are usually offered external cephalic version (ECV) because a persistent breech presentation is often delivered by planned cesarean, which is associated with a clinically significant decrease in perinatal/neonatal mortality and neonatal morbidity compared with vaginal birth.

This topic will provide an overview of major issues related to breech presentation, including choosing the best route for delivery. Techniques for breech delivery, with a focus on the technique for vaginal breech delivery, are discussed separately. (See "Delivery of the singleton fetus in breech presentation".)

TYPES OF BREECH PRESENTATION — The main types of breech presentation are:

●Frank breech – Both hips are flexed and both knees are extended so that the feet are adjacent to the head (figure 1); accounts for 50 to 70 percent of breech fetuses at term.

●Complete breech – Both hips and both knees are flexed (figure 2); accounts for 5 to 10 percent of breech fetuses at term.

●Incomplete breech – One or both hips are not completely flexed (figure 3); accounts for 10 to 40 percent of breech fetuses at term.

In the two nonfrank breech presentations, one or both feet (or rarely one or both knees) may present before the buttocks in the birth canal.

Significance — Because the hips are flexed and the knees are extended or flexed in the frank and complete breech presentations, the thighs and trunk pass through the birth canal simultaneously. If this large fetal diameter passes through the birth canal easily, then the aftercoming shoulders and head are likely to pass through easily as well, though a difficult delivery is still possible.

By contrast, in an incomplete breech presentation, one or both hips are not flexed; therefore, the thighs and trunk do not pass through the birth canal simultaneously. This smaller fetal diameter may easily pass through an incompletely dilated cervix (or an inadequate pelvis) followed by entrapment of the shoulders or head, which have larger diameters and require a fully dilated cervix and normal pelvic dimensions unless the fetus is small. Entrapment increases the risks for hypoxic injury and delivery-related trauma. Even before entrapment, the smaller fetal diameter provides space for umbilical cord prolapse, which can also result in hypoxic injury. In a series of planned vaginal breech deliveries (284 complete or incomplete breech, 884 frank breech), umbilical cord prolapse was more common in nonfrank breech presentations and was the reason for cesarean birth in 5/63 (7.9 percent) complete or incomplete breech presentations versus 3/222 (1.4 percent) frank breech presentations [1]. The overall cesarean birth rate was similar for both groups (nonfrank breech 22.2 percent, frank breech 25.1 percent). (See "Umbilical cord prolapse".)

PREVALENCE — The prevalence of breech presentation at <28 weeks, 32 weeks, and term is approximately 20 to 25, 7 to 16, and 3 to 4 percent, respectively [2,3]. Breech presentation is more common earlier in pregnancy because the fetus can be highly mobile within the relatively large volume of amniotic fluid.

PATHOGENESIS — Breech presentation appears to be a chance occurrence in most pregnancies. In up to 15 percent of cases, however, it may be due to fetal, maternal, or placental abnormalities. It is hypothesized that a fetus with normal anatomy, activity, amniotic fluid volume, and placental location adopts the cephalic presentation near term because this position is the best fit for the intrauterine space, but if any of these variables is abnormal, then breech presentation is more likely.

RISK FACTORS — Multiple factors have been associated with an increased risk for breech presentation, including:

●Preterm gestation

●A previous sibling or either parent who was in breech presentation (see 'Risk of recurrence' below)

●Uterine abnormality (eg, bicornuate or septate uterus, fibroid) [4,5]

●Placental location (eg, placenta previa, cornual placenta) [6,7]

●Extremes of amniotic fluid volume (polyhydramnios, oligohydramnios)

●Nulliparity [8-10]

●Contracted maternal pelvis [11]

●Fetal anomaly (eg, anencephaly, hydrocephaly, sacrococcygeal teratoma, neck mass) [12]

●Extended fetal legs [13]

●Crowding from multiple gestation

●Fetal neurologic impairment

●Maternal hypothyroidism [8]

●Short umbilical cord [14]

●Fetal growth restriction [9]

●Fetal asphyxia [15]

●Female sex [9,16]

●Maternal anticonvulsant therapy [17]

●Older maternal age [9]

Risk of recurrence — Population-based registries indicate an increased risk of recurrent breech presentation [18,19]:

●After one pregnancy with breech presentation, the frequency of recurrence in the next pregnancy is approximately 9 percent

●After two consecutive pregnancies with breech presentation, the frequency of recurrence in the next pregnancy is approximately 25 percent

●After three consecutive pregnancies with breech presentation, the frequency of recurrence in the next pregnancy is almost 40 percent

By comparison, if the first pregnancy is not a breech presentation, the frequency of breech presentation in the next pregnancy is approximately 2 percent.  

Recurrence is usually attributed to recurrent fetal, maternal, or placental abnormalities. However, the possibility of a heritable component to fetal presentation that can be transmitted from either parent was suggested by the observation that parents who themselves were delivered at term from breech presentation were twice as likely to have firstborn offspring in breech presentation compared with parents who were born as a cephalic presentation [20].

CLINICAL FINDINGS AND COURSE — Clinical assessment of fetal presentation should be a routine part of prenatal examination in late pregnancy since breech presentation affects antepartum and intrapartum management. (See 'Approach to management at or near term' below.)

Symptoms — Symptoms of breech presentation are most common in the third trimester. Patients often report subcostal discomfort because the fetal head is in the fundus [21]. They may also perceive kicking in the lower abdomen when the breech is complete or incomplete.

Physical examination — Breech presentation is most readily appreciated in the third trimester. However, abdominal palpation, even by an experienced clinician, may misdiagnose the presentation.

●On transabdominal examination of the lower uterine segment, breech presentation is characterized by the presence of a soft mass (ie, buttocks) and the absence of a hard fetal skull. In addition, a hollow (fetal neck) next to the presenting part is absent in a breech presentation and palpable in a cephalic presentation.

●On examination of the fundus, the fetal head can be readily balloted since it pivots on the neck and moves independently from the trunk. In comparison, in cephalic presentation, ballottement of the breech in the upper part of the uterus is typically sluggish because it is accompanied by movement of the entire trunk.

●On transvaginal examination, the soft buttocks, anal orifice, or feet may be identified when the cervix is dilated but can be difficult to palpate when the cervix is closed. A foot is differentiated from a hand by the presence of the heel, while palpating a fist or a grasp may identify a hand.

Imaging — Ultrasound clearly identifies the fetal head in the fundus, buttocks in the lower uterine segment, extension or flexion of each hip and knee, and location of each foot.

Hyperextension of the fetal head (defined by an extension angle greater than 90 degrees) is an important finding as it is a contraindication to vaginal birth. (See "Delivery of the singleton fetus in breech presentation", section on 'Criteria for minimizing risk in patients who opt for vaginal breech birth'.)

Natural history — Spontaneous version may occur at any time before labor, even after 40 weeks of gestation. In a prospective longitudinal study using serial ultrasound examinations, spontaneous version from breech to cephalic presentation after 36 weeks occurred in 25 percent of cases [13]. In the Term Breech Trial in which patients with breech presentation at ≥37 weeks of gestation were randomized to planned cesarean or vaginal birth, cephalic birth occurred in approximately 2 percent of those allocated to planned cesarean and 4 percent of the planned vaginal birth group, suggesting that additional spontaneous cephalic versions occurred during expectant management until the onset of spontaneous labor [22].

Characteristics that reduce the likelihood of spontaneous version include extended fetal legs, oligohydramnios, short umbilical cord, fetal/uterine abnormalities, and nulliparity.

DIAGNOSIS — The diagnosis of breech presentation should be suspected in patients who describe subcostal discomfort or kicking in the lower abdomen in late pregnancy. The diagnosis is confirmed by identifying the buttocks and/or feet as the presenting part on physical examination (transabdominal and/or transvaginal) or ultrasound examination (ultrasound is more reliable).

Our approach — Antepartum, our practice is to routinely perform a careful abdominal examination in late pregnancy to determine fetal presentation, with the addition of ultrasound examination if the presentation is not identifiable with certainty, as the diagnosis informs decision making around external cephalic version (ECV) and route of delivery. However, physical examination is not infallible [23,24]. In a study in which an experienced clinician examined 138 patients at 30 to 41 weeks of gestation immediately before an ultrasound examination, the examiner identified only three of eight breech presentations and falsely diagnosed six breeches [23]. Physical examination is fallible because characteristic findings of breech presentation on transabdominal examination may be obscured or distorted in patients with obesity, full bladder, leiomyoma, polyhydramnios, anterior placenta, or multiple gestation. Because ultrasound detects 100 percent of breech presentations at the time of the examination, performing ultrasound for fetal presentation in late pregnancy in conjunction with offering external cephalic version may be cost-effective [25,26].

We also routinely perform an ultrasound examination in laboring patients to confirm suspected breech presentation and the type of breech when physical findings are uncertain since sonographic confirmation of a previously unsuspected breech presentation should prompt a discussion about cesarean versus vaginal birth.

Intrapartum differential diagnosis

●Face presentation – On intrapartum transvaginal examination through a dilated cervix a frank breech presentation can feel like an edematous face presentation. A useful distinguishing characteristic is that the fetal greater trochanters and anal orifice form a straight line across the buttocks, whereas the malar bones and mouth form a triangle in the face. (See "Face and brow presentations in labor", section on 'Face presentation'.)

●Compound cephalic presentation – On intrapartum transvaginal examination through a dilated cervix, a foot suggests breech presentation but can also occur with a compound cephalic presentation, which often has one or both hands but may have one or both feet or a hand and a foot presenting alongside or in front of the head. A foot can be distinguished from a hand by its three bony protuberances (calcaneous, lateral and medial malleolus), the angle at the level of the calcaneous, and the toes, which are short and lie in the same line with no opposing thumb. On abdominal examination, the diagnosis of breech presentation is supported by palpation of the head in the fundus. Ultrasound confirms the diagnosis. (See "Compound fetal presentation", section on 'Differential diagnosis'.)

APPROACH TO MANAGEMENT AT OR NEAR TERM

Overview — There is general agreement that the breech fetus is at higher risk for asphyxia and traumatic injury during vaginal birth than the cephalic fetus (see 'Significance' above). To minimize the risk of these complications, the choice of delivery route for the term breech fetus is guided by patient values and preferences and provider experience, values, and preferences, taking into account the risks and benefits of the various approaches [27]. The pregnant person's choice of birth route should be informed by unbiased, noncoercive counseling [28]. The choice should be made with due consideration of specific health care environments, individual values and preferences [29], and the limitations inherent in the data described in the following sections of this topic [30-35]. Clinicians should be aware that people with breech presentation may experience a sense of loss of power and autonomy during this process [36].

Four strategies have evolved:

●External cephalic version (ECV) before labor, with a trial of labor if the version is successful and cesarean birth if unsuccessful. This is the most common approach in the United States and many other countries.

●ECV before labor, with a trial of labor if the version is successful. However, if the version is unsuccessful, a trial of labor and vaginal breech birth are offered to patients who have characteristics that are believed to place them at a low risk of labor and delivery-related complications. Cesarean birth is offered to higher risk patients and any patient who declines to attempt a vaginal breech birth. This is the author's approach. (See "Delivery of the singleton fetus in breech presentation", section on 'Criteria for minimizing risk in patients who opt for vaginal breech birth'.)

●Planned cesarean birth for breech presentation, without an attempt at ECV.

●A trial of labor and vaginal breech birth for patients who have characteristics that are believed to place them at a low risk of labor and delivery-related complications, without an attempt at ECV. (See "Delivery of the singleton fetus in breech presentation", section on 'Criteria for minimizing risk in patients who opt for vaginal breech birth'.)

Antepartum maternal postural changes, moxibustion, and acupuncture do not improve the chances of spontaneous version compared with expectant care alone. This evidence is reviewed separately. (See "External cephalic version", section on 'Postural maneuvers to facilitate spontaneous version' and "External cephalic version", section on 'Moxibustion and acupuncture'.)

Strategy #1: ECV, cesarean birth if unsuccessful — ECV at or near term, followed by a trial of vaginal birth if the version is successful and planned cesarean birth if breech presentation persists is the preferred approach to delivery of the term breech fetus in the United States, and many other countries [27]. Patients are encouraged to undergo ECV to convert a breech presentation to cephalic presentation and thus increase the likelihood of vaginal cephalic birth. If ECV is unsuccessful or the fetus reverts to breech, one or two retrials of version can be attempted in one or more days. In a meta-analysis of randomized trials, ECV at term resulted in a 60 percent reduction in noncephalic presentation at birth (relative risk [RR] 0.42, 95% CI 0.29-0.61) and a 40 percent reduction in cesarean birth (RR 0.57, 95% CI 0.40-0.82) [37]. Performing the version at 34 to 35 weeks of gestation, using a tocolytic drug, and/or administering neuraxial anesthesia increase the likelihood of success, but overall benefits are uncertain. These data and the timing and procedure for ECV are discussed separately. (See "External cephalic version".)

Planned cesarean birth for persistent term breech presentation is associated with a clinically significant decrease in perinatal/neonatal mortality and neonatal morbidity, with only a modest increase in short-term maternal morbidity, compared with a policy of planned vaginal birth. It should be performed at ≥39+0 weeks of gestation to allow optimal physiologic maturation (unless there are specific indications for earlier delivery). Delaying cesarean birth until at least 39+0 weeks is particularly important when the indication is breech presentation, as spontaneous version may occur at any gestational age.

However, a policy of planned cesarean birth may not be affordable or feasible in resource-limited settings. On an individual-case basis, there may be clinical situations in which the maternal risks of cesarean or the patient's desire to avoid cesarean birth outweigh the newborn's risks from vaginal birth. Both birth routes have similar long-term maternal outcomes and childhood outcomes in survivors, and some data suggest some long-term health benefits from being born vaginally, including reduced risk of childhood conditions such as asthma and arthritis [38-40]. In addition, cesarean birth has implications for patients planning future pregnancies, including repeat cesarean birth and increased risks for serious morbidity and mortality associated with placenta accreta spectrum [41] and uterine rupture [42]. Pregnancies following preterm breech cesarean birth versus preterm breech vaginal birth have been associated with increased neonatal acidosis and intensive care admission [43] and other adverse neonatal and maternal outcomes [44]. Lastly, the current policy is largely based on a single randomized multicenter international trial (see 'Evidence' below). Increasing the magnitude of planned cesarean births worldwide will increase the absolute number of patients who develop rare but life-threatening complications of this major operative procedure [45,46]. For example, in Africa, overall maternal mortality from cesarean birth is 0.5 percent [47].

Evidence — The evidence supporting planned cesarean birth was provided by a systematic review of randomized trials of planned cesarean versus planned vaginal birth for term breech presentation (three trials, 2396 participants) [48]. In two of the trials, which were from the same unit, patients with frank [49] or nonfrank [50] breech presentation were randomly assigned to undergo planned cesarean birth or a protocol allowing vaginal birth within prescribed limitations, including the absence of diminished pelvic dimensions on radiographic pelvimetry. The third trial, the Term Breech Trial, was a large (2088 participants) multicenter, international trial comparing planned cesarean with planned vaginal birth by an experienced clinician following agreed upon clinical guidelines [22]. The participating countries were classified as having low or high perinatal mortality rates (low ≤20 deaths per 1000 live births plus late fetal deaths, high >20 deaths per 1000 live births plus late fetal deaths). Cesarean birth was performed in 550 of 1227 patients (45 percent) allocated to the vaginal birth protocol.

The key findings were as follows:

Compared with planned vaginal birth of breech presentation, planned cesarean [48]:

●Reduced perinatal/neonatal death (RR 0.29, 95% CI 0.10-0.86). Risk ratios were similar for countries with low versus high national perinatal mortality rates, but absolute mortality rates were higher in the latter. Subsequently, others estimated that 338 cesareans for breech presentation need to be performed to prevent one perinatal death [51].

●Reduced composite short-term outcome of perinatal/neonatal death or serious neonatal morbidity (RR 0.33, 95% CI 0.19-0.56). This result was largely driven by data from countries with low national perinatal mortality rates, where the comparative risk of the composite outcome was RR 0.07 (95% CI 0.02-0.29; 4/1000 for planned cesarean versus 57/1000 for planned vaginal birth). In countries with high national perinatal mortality rates, the comparative risk of the composite outcome was RR 0.66 (95% CI 0.35-1.24; 29/1000 for planned cesarean versus 44/1000 for planned vaginal birth). The unexpectedly low absolute composite mortality/morbidity rate with planned vaginal birth in high perinatal mortality rate countries may have been due to less macrosomia, more experience with vaginal breech birth, and documentation issues.

The number of adverse events in the meta-analysis was small, thus reducing the chances of detecting statistically significant reductions in birth trauma and brachial plexus injury with planned cesarean birth.

In addition:

●Route of planned birth had no significant effect on long-term outcome in offspring, except that infant medical problems were significantly increased following planned cesarean birth. The combined risk of death/neurodevelopmental delay was similar for the planned vaginal and planned cesarean groups at two years of age. Since there were few serious adverse events despite the large number of study participants and 17 of 18 neonates with serious early morbidity were neurologically normal at two years of age, a small difference between groups in long-term composite mortality/morbidity cannot be excluded.

●Route of planned birth had no significant effect on long-term maternal outcome. In the short-term, planned cesarean resulted in a small increase in some maternal morbidities (eg, hemorrhage, transfusion, infection), but less urinary incontinence and incontinence of flatus. Complications in future pregnancies related to scarring of the uterus were not assessed.

A meta-analysis of 21 cohort studies including nearly 400,000 pregnancies support these findings [52].

The Term Breech Trial impacted clinical practice worldwide: The rate of planned vaginal breech birth fell substantially since publication of this trial [53-57]. In 2016, the cesarean birth rate for breech presentation in European countries was ≥70 percent and approximately 95 percent in the United States [58]. Limited observational data suggest that this fall in planned vaginal breech birth has been accompanied by a fall in the morbidity and mortality of breech birth [51,53], especially if performed before labor begins [59].

Strategy #2: ECV, trial of vaginal birth for selected patients if unsuccessful — The author's preference is to offer ECV followed by a trial of vaginal birth if successful. If unsuccessful, he offers planned cesarean birth, and, for patients who meet criteria, he also offers a trial of labor and vaginal breech birth [30-35,38-40,42,45,46]. There is a general consensus that patients who choose to undergo a trial of labor and vaginal breech birth should be at low risk of complications from vaginal breech birth and their labor and birth should be supervised by a clinician with experience in vaginal breech birth. Whether such pregnancies can be identified and how the fetal risks from vaginal birth compare with maternal risks from cesarean birth have been debated for decades. (See "Delivery of the singleton fetus in breech presentation", section on 'Criteria for minimizing risk in patients who opt for vaginal breech birth'.)

Closely monitoring the progress of labor is particularly important in patients who attempt a vaginal breech birth. The author has a low threshold for performing a cesarean birth if he believes that labor progress is inadequate. His criteria for abnormal labor progress are described in detail separately. (See "Delivery of the singleton fetus in breech presentation", section on 'Labor management'.)

Evidence — The PREsentation et MODe d'Accouchement (PREMODA) study is often cited as the best evidence to support vaginal breech birth in selected patients [60]. The results of this observational study are less robust than those of the Term Breech Trial discussed above but provide information illustrating the magnitude of morbidity/mortality of planned vaginal birth in patients managed using the authors' protocol. Subsequent smaller prospective observational studies have also reported low rates of adverse outcome from planned vaginal breech birth that followed strict protocols [61-65], including first pregnancies [66] and pregnancies beyond the estimated due date [67].

PREMODA was a prospective observational multicenter study conducted in 174 centers in France and Belgium and including 8105 singleton breech fetuses at term [60]. The study evaluated the safety of vaginal breech birth using strict criteria (table 1) for selecting patients for a trial of labor. Major findings were [60,68]:

●The composite outcome of fetal/neonatal mortality or serious neonatal morbidity was not significantly different for planned vaginal versus planned cesarean birth (1.60 versus 1.45 percent, odds ratio 1.10, 95% CI 0.75-1.61) after adjustment for geographic origin, gestational age less than 39 weeks at birth, birth weight less than the 10^th percentile, and an annual number of maternity unit births of less than 1500.

●Approximately 70 percent of the 2502 patients in the planned vaginal birth group delivered vaginally, and 165 (6.6 percent) of these pregnancies had an adverse perinatal outcome, including but not limited to brachial plexus injury (five infants), skull fracture (one infant), genital injury (two infants), intraventricular hemorrhage (one infant), seizure (four infants), and death (two infants). Factors associated with adverse perinatal outcome were geographic origin, delivery at <39 weeks of gestation, birth weight <10^th percentile, and annual number of maternity unit births <1500.

Strategy #3: Cesarean birth without ECV — Some patients may choose to undergo a planned cesarean birth without an attempt at ECV. Patients with a low likelihood of successful version or at increased risk of fetal harm from the procedure may reasonably avoid an attempt at version and choose cesarean birth. (See "External cephalic version", section on 'Candidates'.)

Strategy #4: Vaginal birth without ECV — Some patients may choose to undergo a trial of labor and vaginal breech birth without an attempt at ECV. Those with a low likelihood of successful version or at increased risk of fetal harm from the procedure may reasonably avoid the procedure and choose to attempt vaginal birth (see "External cephalic version", section on 'Candidates'). As discussed above, there is a general consensus that patients who choose to undergo a trial of labor and vaginal breech birth should be at low risk of complications from vaginal breech birth and their labor and birth should be supervised by a clinician with experience in vaginal breech birth. (See "Delivery of the singleton fetus in breech presentation", section on 'Criteria for minimizing risk in patients who opt for vaginal breech birth'.)

APPROACH TO MANAGEMENT OF PRETERM BREECH BIRTH — In most cases, cesarean is preferred for birth of the preterm breech fetus because the body of evidence from observational studies suggests that vaginal birth of the very preterm breech fetus is likely associated with a small but significant increase in adverse outcome that can be avoided by cesarean birth. The preterm fetal head circumference-to-abdominal circumference ratio is larger than that of a term fetus; thus, the preterm breech head is more likely to be entrapped in a partially dilated cervix, resulting in birth trauma and/or acute asphyxia from compression of the umbilical cord [69,70].

●In a 2014 systematic review of seven observational studies (3557 participants) that evaluated cesarean versus vaginal birth of the preterm breech, the weighted risk of neonatal mortality was lower in the cesarean group than in the vaginal birth group (3.8 versus 11.5 percent, pooled relative risk 0.63, 95% CI 0.48-0.81) [71]. In one of the included studies, a retrospective study of patients delivering breech infants at 26 to 29 weeks of gestation, the rate of head entrapment was twofold higher in the planned vaginal birth group than in the planned cesarean birth group (11/84 [13 percent] versus 5/85 [6 percent]) [70]. Four neonatal deaths were attributed to head entrapment; three of these infants were delivered vaginally and died within an hour of birth (neonatal death related to head entrapment 3/45 vaginal births versus 1/124 cesarean births). The single infant that died after cesarean birth complicated by head entrapment died five days later because of sepsis and grade 3 intraventricular hemorrhage. Of note, approximately 50 percent of planned vaginal births ended in cesarean birth, while 6 percent of planned cesareans ended in vaginal birth.

The authors of the systematic review subsequently published a cohort study including over 8300 patients with a singleton preterm fetus in breech presentation who delivered at 26+0 to 36+6 weeks of gestation in the Netherlands from 2000 to 2011 [72]. A strength of this study is the large number of participants who intended to deliver vaginally (6421), although 2995 of these individuals delivered by emergency cesarean during labor. Compared with intended vaginal birth, intended cesarean birth was not associated with a significant reduction in perinatal mortality (1.3 versus 1.5 percent, adjusted odds ratio [OR] 0.97, 95% CI 0.60-1.57) or the composite outcome of perinatal mortality/severe morbidity (3.2 versus 4.1 percent, adjusted OR 0.76, 95% CI 0.56-1.03); however, when minor morbidities such as five-minute Apgar score <7 were also considered, intended cesarean birth reduced the rate of the composite outcome of perinatal mortality/morbidity (8.7 versus 10.4 percent, OR 0.77, 95% CI 0.63-0.93). A subgroup analysis based on gestational age found that perinatal mortality, morbidity, and severe morbidity were significantly reduced by cesarean at 28 to 32 weeks of gestation.

●In a 2018 meta-analysis to determine the safest route of delivery of actively resuscitated extremely preterm (23+0 to 27+6 weeks) breech singletons, cesarean was associated with reductions in the odds of death by 41 percent (OR 0.59, 95% CI 0.36-0.95, number needed to treat [NNT] 8) and of severe intraventricular hemorrhage by 49 percent (OR 0.51, 95% CI 0.29-0.91, NNT 12) [73]. Infants at lower gestational ages experienced the greatest benefit. Data from one randomized trial, one prospective cohort study, and 13 retrospective cohort studies were combined for the analysis.

TECHNIQUE FOR BREECH DELIVERY — (See "Delivery of the singleton fetus in breech presentation".)

NEONATAL OUTCOME — Newborns that were in breech presentation have increased morbidity and mortality; however, breech presentation itself probably is not an independent risk factor for adverse neonatal outcome [74,75]. Rather, adverse outcomes are related, in part, to underlying conditions associated with breech presentation (eg, congenital anomalies, fetal growth restriction, preterm birth) and, in part, to birth trauma, which is often related to vaginal breech birth.

Regardless of route of birth, neonates who are breech in utero are more likely to have congenital anomalies [76] (4.4 versus 2.4 percent in vertex presentation [77]) and mild deformations (eg, frontal bossing, prominent occiput, upward slant, and low-set ears), torticollis, and developmental dysplasia of the hip [78-80], which may present late despite normal initial ultrasound evaluation [81]. Ultrasonography at four to six weeks of age (adjusted for preterm birth) has been recommended for infants with an abnormal hip examination or a normal examination and breech position at ≥34 weeks of gestation. (See "Congenital muscular torticollis: Clinical features and diagnosis" and "Developmental dysplasia of the hip: Epidemiology and pathogenesis", section on 'Breech position'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Breech presentation and external cephalic version".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Breech pregnancy (The Basics)" and "Patient education: External cephalic version (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Types – Breech presentation may be frank, complete, or incomplete (figure 1 and figure 2 and figure 3). (See 'Types of breech presentation' above.)

●Prevalence – Breech presentation complicates 3 to 4 percent of pregnancies at term; the prevalence is inversely associated with gestational age. (See 'Prevalence' above.)

●Pathogenesis – In most pregnancies, breech presentation is a chance occurrence. In up to 15 percent of cases, it may be due to fetal, maternal, or placental abnormalities. (See 'Pathogenesis' above.)

●Symptoms – Symptoms of breech presentation include subcostal discomfort from the fetal head in the fundus and kicking in the lower abdomen when the breech is complete or incomplete. (See 'Symptoms' above.)

●Diagnosis – The diagnosis of breech presentation is based on identifying the buttocks and/or feet as the presenting part on physical examination (transabdominal or transvaginal) or ultrasound examination. (See 'Diagnosis' above and 'Physical examination' above and 'Imaging' above.)

●Management

•Overview – The management of breech presentation at term is guided by patient values and preferences and provider experience, values, and preferences after review of the evidence of the risks and benefits of available interventions. (See 'Approach to management at or near term' above.)

The choice of birth route should be made with due consideration of specific health care environments, individual patient values and preferences, and the limitations inherent in available evidence. A policy of planned cesarean birth may not be affordable or feasible in resource-limited settings. On an individual case basis, there may be clinical situations in which the risks of cesarean to the patient, or the patient's desire to avoid cesarean birth, may outweigh the newborn's short-term risks from vaginal birth. Both birth routes have similar long-term maternal and childhood outcomes, and some data suggest some long-term health benefits to being born vaginally. In addition, cesarean birth has implications for patients planning future pregnancies, including repeat cesarean birth and increased risks of placenta accreta spectrum and uterine rupture. (See 'Approach to management at or near term' above.)

•Role of external cephalic version – In the United States, clinician preference for pregnancies with breech presentation is to offer the patient external cephalic version (ECV) at or near term, followed by a trial of vaginal birth if the version is successful and planned cesarean if breech presentation persists because planned cesarean birth of the breech fetus reduces perinatal death or severe morbidity. (See 'Strategy #1: ECV, cesarean birth if unsuccessful' above.)

•Role of planned cesarean birth – Some patients may choose to undergo planned cesarean birth if the breech persists without an attempt at ECV. Patients with a low likelihood of successful version or at increased risk of fetal harm from the procedure may reasonably avoid the procedure. (See 'Strategy #3: Cesarean birth without ECV' above.)

•Role of vaginal breech birth – Some patients may choose to have a vaginal breech birth. There is a general consensus that these patients should be at low risk of complications from vaginal breech birth and their labor and delivery should be supervised by a clinician with experience in vaginal breech birth. (See 'Strategy #2: ECV, trial of vaginal birth for selected patients if unsuccessful' above.)