Breech Presentation

Epidemiology

Breech presentation is a normal variant, occurring in up to 4% of term and 25% of preterm births. It is more common in nulliparous women (60%), where there are uterine or fetal abnormalities, placental praevia or another pelvic obstruction, and where there has been a previous breech baby (8% risk), but most are idiopathic. Both maternal and paternal genetic influences (family history) appear to be important.

Clinical Features, Diagnosis and Investigations

The first key to the prevention of breech birth is its identification. The diagnosis becomes important from 36 weeks in nulliparous women, after which time spontaneous version occurs in <10%, and from 37 weeks in multiparous women because spontaneous version may occur later, and in labour. The woman may feel discomfort or the head under her ribs, or kicks low down; the examiner will feel a head under ribs or find the presenting part to be soft and not ballotable. In the absence of routine third trimester ultrasound, approximately one-third are missed. A routine scan at 36 weeks appears to reduce this to <5%.

Where breech presentation is suspected in the late third trimester, an ultrasound examination should document the estimated fetal weight (EFW), the umbilical artery pulsatility index (PI), and perhaps even the cerebroplacental ratio (CPR), the type of breech, whether the neck is extended, and the liquor volume. A re-examination for the presence of a fetal or uterine abnormality and placental position is also wise.

At least half of breech babies are ‘frank’ or ‘extended’: the legs are extended at the knee in front of the body ( Fig. 20.1a ). In a flexed breech ( Fig. 20.1b ), the knees are flexed with the feet in front of the pelvis. In a footling breech ( Fig. 20.1c ), one or both feet are below the buttocks, and therefore presenting.

Prevention of Breech Presentation: External Cephalic Version

The second key to the prevention of breech birth is external cephalic version (ECV). Even if vaginal breech birth would be planned this remains true because of the higher risk of intrapartum caesarean section during breech birth. Assessment of suitability for, and discussion of, ECV should take place at 36 and 37 weeks in nulliparous and multiparous women, respectively.

Method of ECV

There are many methods to achieve version and one is described. Neither starvation nor IV access are necessary. CTG prior to the procedure is usual. Tocolysis with either 250 μg of salbutamol in 25 mL of normal saline (10 μg/mL) by slow IV injection, or 250 μg of terbutaline subcutaneously are easiest to use. Regional anaesthesia is said to require less force but is very labour and resource intensive and should be reserved for where maternal discomfort prevents version. We perform ECV in a single weekly clinic; this ‘one stop clinic’ allows confirmation of the presentation, counselling about ECV, performance of ECV and discussion and planning of the birth ( Fig. 20.2 ). ECV requires consent and more than 10% of women will decline it.

The woman lies almost recumbent, with the abdomen exposed ( Fig. 20.3 ). Good, continuous communication and eye contact are needed. Maternal abdominal wall relaxation can be aided using breathing exercises. We use a clean abdomen or ultrasound gel; talc is advocated by some. A forward roll is the aim: with flexed legs only, a backward roll is reasonable if the forward one fails. Both thumbs may be used, or the end of several fingers. In most cases, the breech will need to be brought up from the pelvis by first pushing the thumbs or fingers down between it and the symphysis pubis. This is not required if the breech is free. The breech is then pushed progressively towards the side of the fetal back, aiming to reach almost 3 or 9 o’clock. In some cases, this will cause the head to go under the ribs: if this occurs, the procedure should stop and a helper place the side of their hand vertically between the head and the ribs, to encourage lateral movement of the head. The woman should be encouraged to keep her abdominal muscles lax: this is difficult. Care should be taken not to push too hard, particularly when the abdomen is lax. If the baby reaches a transverse lie, success is likely: a second hand, or that of a helper, is placed behind the baby’s head, which is pushed downwards towards the pelvis, while the breech is lifted further. The single operator may swap hands around at this point. After ECV, the head will initially be very high, or there may be legs, cord or even a hand below it. These will move within an hour in most women, and in almost all within 12 hours. Failure is usually because the breech cannot be brought out of the pelvis, or cannot be moved up far enough.

In general more than four attempts are futile, as is a total ECV time of over 10 minutes. The fetal heart is observed every 1–2 minutes, and immediately after the procedure; CTG is started immediately. This is continued until three accelerations from a normal baseline are seen. The woman is advised to move to the left lateral, or to sit up. If the woman is Rhesus negative and the baby not known to be Rhesus negative, a Kleihauer test is taken and anti-D administered.

Mode of Birth for the Breech Baby

Vaginal breech birth, planned or not, was becoming uncommon in most developed countries even before the Term Breech Trial. This study suggested an excess 1% perinatal mortality with planned vaginal breech birth, and a number needed to treat of nine to prevent ‘serious short-term morbidity’. Subsequent data and debate over the trial cast doubts over the true risks attributable to breech birth, but caesarean section remains the norm in the majority of Western countries and units. A serious consequence is a loss of skills. In the not uncommon situation where the breech presentation is undiagnosed until late labour, or where the mother wishes to give birth vaginally, risk may have been increased because of lack of experience on the part of midwives and doctors. It also now seems that the risks of serious adverse sequelae of an attempt at vaginal breech birth were exaggerated by the Term Breech Trial.

Criticisms of this trial have included that results from women randomized in violation of the protocol were included, that case selection was inappropriate (31% had no ultrasound prior to labour, growth-restricted babies were included, and there were size differences in the two groups) and that management was unconventional (oxytocin and a prolonged active second stage could be used, an obstetrician was absent in 13% of cases, and CTG was not required). Further, ‘serious neonatal morbidity’ encompassed some frequently benign outcomes (such as isolated large base deficit) and was twice as common in countries with a low perinatal mortality rate. Glezerman commented that in only 16 (23%) of 69 neonates with the primary outcome could this be related to mode of delivery. Doubts over the validity of ‘serious neonatal morbidity’ were compounded by the 2-year follow-up of 923 out of 1159 children showing no difference in longer-term disability among survivors.

The improved safety of caesarean section for the breech fetus is, however, not disputed; it is the degree of safety conferred that should be. Vlemmix et al compared breech birth before and after the publication of the breech trial in a population-based cohort study of 58,320 nonanomalous term breech babies in the Netherlands. The perinatal mortality of breech babies halved from 0.13% to 0.07% (odds ratio 0.51; 95% confidence interval 0.28–0.93), in association with an increase in caesarean section, but there remained a 0.16% rate in the planned vaginal birth group. These babies were alive at the start of the birth process (the perinatal mortality rate was 0 in the elective caesarean births) so an absolute risk of 1.6/1000 attributable to birth can be inferred. A meta-analysis of 27 studies (258,953 births between 1993 and 2014) suggested a 3/1000 risk. Goffinet et al reported on 2526 vaginal birth attempts using strict selection and management criteria and reported a 0.8/1000 perinatal mortality. These compare favourably with the 10/1000 perinatal mortality figure in the Term Breech Trial.

Short-term morbidity should nevertheless not be ignored. Although fairly consistently worse than caesarean section, this is better in the French series, and in many other, smaller series than in the Term Breech Trial. Although the data varies, in general planned vaginal birth shows significant increases in low Apgar scores and total injuries, most of which were clavicular fractures or haematomata. Neonatal unit admissions, although not significantly increased in the French series, are also probably more common.

It is reasonable to infer that elective caesarean is slightly protective against perinatal mortality for any baby for two reasons: it is usually performed before 40 weeks so there is less opportunity for antepartum stillbirth, and it virtually eliminates birth-related risk. In a pregnancy where the baby is cephalic, these risks add up to approximately 2/1000. Yet routine caesarean section is not widely advocated for cephalic babies. Where the baby is breech, there is an additional, birth-related (if the baby is not congenitally abnormal) risk of about another 1/1000. This situation is not markedly different from vaginal birth after caesarean section (VBAC), a not uncommon scenario in European delivery wards.

A further consideration should be future pregnancies, and the maternal risk of caesarean section: of both uterine rupture and placenta accreta spectrum. In women who are older or planning small families, placenta accreta is less important. The risk of hysterectomy after one caesarean section is 0.31%, rising to 2.33% after four In women planning large families, this should be a major consideration during counselling. In women where access to healthcare is very poor, the subsequent maternal risk of caesarean section is likely to be much greater: uterine rupture would be almost inevitably catastrophic for the mother. There are also emerging data suggesting, but not proving, a relationship between birth by caesarean section and later morbidity, including obesity, diabetes and atopic conditions, as well as a disputed association with stillbirth in subsequent pregnancies.

Criteria for Safest Vaginal Breech Birth

Although evidence is poor, it is reasonable to ‘select’ pregnancies in women considering vaginal breech birth where risks are likely to be least: recommended criteria are based on what evidence there is, from selection criteria for series with good results, and using logic. Such selection should constitute a recommendation. In general, such contraindications to planned breech birth are where the baby is thought to be large (3.8–4.0 kg is a common cut off), growth restricted (the surrogate of 2.5 kg is often used), where the neck is extended, or the legs footling. The role of pelvimetry is unclear: we do not use it, nor is it recommended by the RCOG, although it was used in 82.5% of pregnancies in the series where vaginal birth had the lowest risk of complications.