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Vaginal Breech Delivery in Term Singletons Can No Longer Be Justified

Charles J. Lockwood, MD

More than 80% of term singleton fetuses with a breech presentation are currently delivered by cesarean delivery in the United States.¹ This trend away from vaginal breech delivery raises several questions:

• Why have American OB/GYNs "voted with their feet" to essentially eliminate this ancient and elegant component of the accoucheur’s art?
• Is abandonment of term breech trials of labor justified?
• Is it time for academicians to recommend cesarean delivery for breech presentations?

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INITIAL STUDIES

Background

Over the past decade, a series of papers have generated momentum against term breech trials of labor. In 1993, Cheng and Hannah² conducted a critical review of 24 articles published between 1966 and 1992 comparing obstetric outcomes following planned vaginal delivery versus planned cesarean delivery in patients with term singleton breech presentations. They observed that perinatal mortality was substantially higher in the planned vaginal delivery group, with a typical odds ratio (OR) of 3.86 (95% confidence interval [CI]: 2.22 to 6.69). Similarly, neonatal morbidity due to trauma was also higher in the planned labor group, with a typical OR of 3.96 (CI, 2.76 to 5.67). In 1995, Gifford and associates3 conducted a meta-analysis of both randomized trials and cohort studies on breech delivery published between 1981 and 1993. They included studies that provided criteria for vaginal delivery as well as outcomes data, thus allowing for analysis by intended mode of delivery. The nine studies that met these requirements demonstrated a more than 10-fold increased risk of perinatal or neonatal injury or death in the trial-of-labor patients compared with the elective cesarean delivery patients.

In 1998, Koo and colleagues⁴ conducted a case-control study of 306 term singleton breech deliveries occurring between 1989 and 1994. There were 170 infants delivered vaginally, 72 by elective cesarean delivery, and 64 by secondary cesarean delivery. After applying strict selection criteria including the presence of a clinically adequate pelvis, an estimated fetal weight of 2,500 to 4,000 g, and experienced supervision, they observed that vaginal delivery was associated with a higher incidence of low umbilical artery pH values and more admissions to a neonatal intensive care unit (NICU) compared with elective cesarean delivery.

A recent review of the Cochrane registry noted that 45% (550/1,227) of women with term breech presentations assigned to a vaginal delivery protocol were ultimately delivered by cesarean, whereas planned cesarean delivery was associated with significantly reduced risks of perinatal and neonatal death (OR, 0.29; CI, 0.10 to 0.86).⁵ Thus, nearly half of carefully selected, appropriate candidates for a term breech trial of labor eventually required abdominal delivery, and they experienced a more than 3-fold increase in infant mortality despite the high rate of conversion to cesarean delivery. Thus, prior studies certainly do not support the safety of breech trials of labor even with rigorous inclusion criteria and experienced practitioners.

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THE HANNAH TRIAL⁶

While impressive, these reviews and meta-analyses were limited by their inclusion of small, heterogeneous, prospective, randomized trials, as well as cohort and case-control studies. However, a recent large, prospective, randomized clinical trial by Hannah and associates⁶ has confirmed the findings of these earlier analyses. The goal of this landmark study was to determine whether planned cesarean delivery for breech presentation conferred any benefits compared with planned vaginal birth among women who were good candidates for vaginal delivery by experienced clinicians. Randomization of patients was stratified by parity. Inclusion criteria were restricted to patients with singleton gestations and either frank or complete breech presentation at or beyond 37 weeks’ gestation. Patients were excluded for suspected fetopelvic disproportion, estimated fetal weight greater than 4,000 g, hyperextension of the fetal head, mechanically problematic or lethal fetal anomalies, or contraindication to vaginal delivery (eg, placenta previa).

In the study by Hannah and colleagues,⁶ patients in the elective cesarean delivery group underwent delivery at or after 38 weeks or following confirmation of lung maturity. By contrast, patients in the trial-of- labor group awaited spontaneous labor or postdates induction. The trial-of-labor patients underwent standard fetal heart rate (FHR) monitoring, oxytocin augmentation as needed, and spontaneous or assisted breech delivery. In this group, cesarean deliveries were mandated by footling breech presentations, FHR abnormalities, or a well-defined lack of progress (ie, total labor for more than 18 hours; cervical dilation of less than 0.4 cm/hr; and second stage exceeding 2 hours, including more than 1.5 hours of pushing). Centers were monitored to ensure that only experienced clinicians attended deliveries, and that the stipulated management protocol was followed.

After excluding lethal anomalies, an exhaustive analysis was undertaken based on intention to treat. Outcomes included well-defined indices of perinatal or neonatal mortality and a long menu of indicators of serious morbidity. The occurrence of maternal morbidity or mortality was also analyzed. Multiple logistic regression was employed to test for interactions between baseline characteristics in the treatment groups and outcomes. Evaluation of perinatal and neonatal mortality and serious morbidity considered factors including:

• Effects of maternal age
• Type of breech presentation
• Experience of the obstetrician
• Labor induction
• Need for labor augmentation
• Prolonged labor
• Lack of epidural anesthesia
• Postdates gestational age
• Presence of labor
• Membrane rupture
• Estimated fetal weight
• Actual birthweight
• Method of pelvic assessment
• Prior external cephalic version
• Standard of care at the center
• The country’s World Health Organization perinatal morality rate
• Number of women recruited.

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The sample size was calculated at 2,800, yielding an 80% power to detect a reduction in perinatal and neonatal morality or serious morbidity from 0.8% to 0.1% after elective cesarean delivery. However, an independent monitoring committee stopped the study prematurely because the primary outcomes were significantly different. A total of 2,088 women were enrolled.

While the baseline characteristics of the groups were similar, there were significantly more episodes of cord prolapse, chorioamnionitis, FHR abnormalities, and difficult deliveries in the trial-of-labor group. Fourteen of 16 stillbirths and neonatal deaths followed vaginal delivery. There was also significantly more perinatal and neonatal mortality or serious morbidity in the trial-of-labor group (Table). Most striking was the observation that the greatest benefits of planned cesarean delivery accrued in patients from industrialized nations such as the United States and Canada, with a reduction in relative risk (RR) of perinatal and neonatal mortality and serious morbidity of 0.07 (CI, 0.02 to 0.29). These differences occurred despite a higher cesarean delivery rate in the trial-of-labor group among centers in developed countries (55.3% versus 31.7%).⁶

The reduction in risk accruing in breech presentations delivered by cesarean remained even after excluding cases with less experienced clinicians, labor abnormalities, oxytocin use, and footling or uncertain presentations (RR 0.49 [CI, 0.26 to 0.91]). By contrast, there were no differences in maternal mortality or serious morbidity between the groups. The authors concluded that a policy of planned cesarean delivery for term singletons with frank or complete breech presentation would save one infant from death or serious morbidity for every seven cesarean delivery performed in centers in industrialized countries.⁶

While this study had a number of potential weaknesses, including variable numbers of patients enrolled at the participating centers and a lack of long-term maternal or fetal follow-up, it also had many strengths. These included a solid study design, large sample size, and a meticulous logistic regression analysis to exclude potential confounders. Moreover, it represents the largest and best effort to date at assessing the safety of a trial of labor among patients with term singleton breech presentations. It is very unlikely to be replicated.

There are several caveats to this blanket condemnation of trials of labor in patients with breech presentations at term, though. This contraindication does not apply to twin gestations where the safety of vaginal delivery of a second twin appears well established. Moreover, there are practical limitations to this policy. If a grand multiparous patient presents in active labor with the fetus in breech position at the perineum, it is probably safer for mother and infant to effect a vaginal delivery. Moreover, among patients planning very large families, a risk benefit analysis may favor a trial of labor to avoid the potential morbidities (eg, placenta previa and acreta) associated with multiple cesarean deliveries. Finally, abandonment of term singleton breech trials of labor reinforces the need to offer external cephalic version to patients who have no specific contraindications to the procedure. The success rate for versions ranges from 35% to 86% in the literature, with an average of about 50%.^8,9

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CONCLUSION

It can be argued that American obstetricians are abandoning trials of labor in patients with term singleton breech presentations because of their perception that it was a dangerous practice given the safe alternative of cesarean delivery. Moreover, the accumulated literature clearly justifies this collective view. While it is possible to find specific flaws and imperfections with each of these studies, their cumulative weight is unanswerable. In this author’s view, it is time for US academicians to join their Canadian colleagues⁷ in endorsing planned elective cesarean delivery for persistent term singleton breech presentations.

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REFERENCES

1. Ventura SJ, Martin JA, Curtin SC, et al. Births: final data for 1999. Natl Vital Stat Rep. 2001;49(1):1-100.
2. Cheng M, Hannah M. Breech delivery at term: a critical review of the literature. Obstet Gynecol. 1993;82:605-618.
3. Gifford DS, Morton SC, Fiske M, Kahn K. A meta-analysis of infant outcomes after breech delivery. Obstet Gynecol. 1995;85:1047-1054.
4. Koo MR, Dekker GA, van Geijn HP. Perinatal outcome of singleton term breech deliveries. Eur J Obstet Gynecol Reprod Biol. 1998;78:19-24.
5. Hofmeyr GJ, Hannah ME. Planned caesarean section for term breech delivery. Cochrane Database Syst Rev. 2001;(1): CD000166.
6. Hannah ME, Hannah WJ, Hewson SA, et al. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet. 2000;356:1375-1383.
7. Society of Obstetricians and Gynaecologists of Canada. The Canadian consensus on breech management at term. SOGC Policy Statement No. 31. J SOGC. 1994;16:1839-1848.
8. Van Veelen AJ, Van Cappellen AW, Flu PK, et al. Effect of external cephalic version in late pregnancy on presentation at delivery: a randomised controlled trial. Br J Obstet Gynaecol. 1989:96:916-921.
9. Mahomed K, Seeras R, Coulson R. External cephalic version at term. A randomised controlled trial using tocolysis. Br J Obstet Gynaecol. 1991:98:8-13.

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