Current Commentary
Once More Unto the Breech Planned Vaginal Delivery Compared With Planned Cesarean Delivery K.S. Joseph, MD, PhD, Tracy Pressey, MD, Janet Lyons, MD, MSc, Sharon Bartholomew, Shiliang Liu, MD, PhD, Giulia Muraca, MPH, and Robert M. Liston, MB
This article provides a knowledge-based assessment of planned cesarean delivery compared with planned vaginal delivery for breech presentation at term gestation. The most critical evidence on this issue is the intention-to-treat analysis from the Term Breech Trial, which showed that planned cesarean delivery reduced composite perinatal death and serious neonatal morbidity. Although there was no difference in composite death or neurodevelopmental delay at 2 years of age, this finding was based on only 44% of randomized patients and was not an analysis by intention to treat. On the other hand, the design of the nonexperimental Presentation et Mode d’Accouchement: presentation and mode of delivery (PREMODA) study (which showed no difference in composite perinatal mortality or morbidity after planned cesarean delivery compared with planned vaginal delivery), likely favored the planned vaginal delivery group; lack of exclusion criteria led to higher risk women (with contraindications to vaginal delivery) being included in the planned cesarean delivery group. Such selection bias notwithstanding, both the Term Breech Trial and the PREMODA study showed significantly higher rates of
From the Department of Obstetrics and Gynaecology, University of British Columbia and the Children’s and Women’s Hospital and Health Centre of British Columbia, the School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, and the Maternal and Infant Health Section, Public Health Agency of Canada, Ottawa, Ontario, Canada. Ms. Muraca is supported by a Vanier Canada Graduate Scholarship from the Canadian Institutes of Health Research (CIHR), and Dr. Joseph is supported by an Investigator award from the Child and Family Research Institute and a Chair in Maternal, Fetal and Infant Health Services Research from CIHR. Corresponding author: K.S. Joseph, MD, PhD, Room C403, Department of Obstetrics & Gynaecology, Women’s Hospital of British Columbia, 4500 Oak Street, Vancouver, BC, Canada V6H 3N1; e-mail: [email protected]. Financial Disclosure The authors did not report any potential conflicts of interest. © 2015 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0029-7844/15
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5-minute Apgar score less than 4, 5-minute Apgar score less than 7, intubation, and birth trauma in the planned vaginal delivery group. Finally, studies from the Netherlands, Denmark, and Canada have shown that increases in planned cesarean delivery after the Term Breech Trial led to improved neonatal outcomes. Nevertheless, planned vaginal delivery continues to be associated with higher rates of adverse perinatal outcomes in these countries. The totality of the evidence therefore unequivocally shows the relatively greater safety of planned cesarean delivery for breech presentation at term gestation. (Obstet Gynecol 2015;125:1162–7) DOI: 10.1097/AOG.0000000000000824
T
he past two decades have witnessed a substantial accumulation of evidence regarding the relative merits of different approaches to delivery for breech presentation at term gestation. However, the evolution in understanding with regard to breech delivery has been marked by controversy and some lack of clarity with regard to the merits of planned cesarean delivery compared with planned vaginal delivery. Not surprisingly, there is significant international variation in the mode of delivery for breech presentation at term.1–4 In this article, we discuss key evidentiary issues, including the effects of planned cesarean delivery compared with planned vaginal delivery on short-term compared with longer term outcomes, findings from randomized trials compared with nonexperimental studies, and a knowledge-based approach to informing and supporting women with breech presentation at term.
BREECH DELIVERY AT TERM: A BRIEF HISTORY Until the turn of the century, there was insufficient evidence favoring planned cesarean delivery or planned vaginal delivery. This situation changed with the publication of the Term Breech Trial,5 which
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showed significantly lower rates of composite perinatal mortality and serious neonatal morbidity after planned cesarean delivery compared with planned vaginal delivery. The trial led to immediate and dramatic changes in obstetric practice with the American College of Obstetrics and Gynecology6 and the Royal College of Obstetrics and Gynaecology7 issuing guidelines in 2001 recommending planned cesarean delivery for breech presentation at term. The publication of the Term Breech Trial was followed by a firestorm of criticism and several retrospective studies of planned vaginal delivery8–10 showing excellent neonatal outcomes given carefully specified protocols. The 2-year follow-up of the Term Breech Trial11 was published in 2004 and showed no difference between planned cesarean delivery and planned vaginal delivery with regard to composite death or neurodevelopmental delay. In 2006, the Presentation et Mode d’Accouchement: presentation and mode of delivery (PREMODA) study,12 a large, prospective, nonexperimental study, showed that perinatal mortality and composite perinatal mortality and serious neonatal morbidity were not significantly different between planned cesarean delivery and planned vaginal delivery groups. The alleged shortcomings of the Term Breech Trial, the demonstration of good neonatal outcomes after planned vaginal delivery with careful supervision, the lack of a difference in 2-year outcomes of the Term Breech Trial, and the negative results of the PREMODA study led to a change in attitudes within the obstetric community. In 2006, the American College of Obstetricians and Gynecologists,13 the Royal College of Obstetricians and Gynaecologists,14 and the Society of Obstetricians and Gynaecologists of Canada15 (in 2009) issued guidelines stating that the decision regarding approach to delivery “.should depend on the experience of the health care provider.”13 Whereas planned cesarean delivery remained the preferred management option, women fully informed about potential risks could reasonably be offered planned vaginal delivery with oversight from a hospital-specific protocol for eligibility and labor management.
seemingly supported by the fact that rates of perinatal death and serious neonatal mortality were significantly elevated in the planned vaginal delivery arm of the Term Breech Trial,5 whereas rates of death and neurodevelopmental delay at 2 years of age were not.11 Interpreting the results from the Term Breech Trial’s primary analysis compared with those from the 2-year follow-up requires consideration of issues related to relevance and validity.16 Clearly, the 2year outcome of composite death or neurodevelopmental delay is conceptually more relevant from a clinical and social standpoint than the immediate primary outcome of perinatal death or serious neonatal morbidity. However, from a validity standpoint, the Term Breech Trial’s contrast of death or neurodevelopmental delay at 2 years of age was compromised because this analysis was not an analysis by intention to treat. The Trial randomized 2,088 women, and information on 2,083 (99.8%) patients was available for the intention-to-treat analysis of perinatal mortality or serious neonatal morbidity.5 On the other hand, for the analysis of death or neurodevelopmental delay at 2 years of age, follow-up was planned for children from 85 of 121 centers, and of the 1,159 children from these centers, only 923 (44.2% of those randomized) were examined at 2 years of age.11 Because randomization was not stratified by center and given a greater than 50% loss postrandomization, the findings of the 2-year analysis have to be interpreted as those from a cohort study with a substantial loss to follow-up. The relatively greater relevance of the 2-year outcome notwithstanding, the only valid inference supported by the Term Breech Trial results is that perinatal mortality and serious neonatal morbidity rates are significantly reduced after planned cesarean delivery.
EVIDENCE FROM THE TERM BREECH TRIAL COMPARED WITH EVIDENCE FROM THE PREMODA STUDY
One misconception with regard to the Term Breech Trial is the belief that planned vaginal delivery increases the risk of acute, short-term outcomes but does not increase the risk of the more relevant and devastating long-term outcomes.15 This position is
The Term Breech Trial and the PREMODA study showed very different results with regard to perinatal mortality, composite perinatal mortality and neonatal morbidity, and serious neonatal morbidity. Rate ratios expressing the effect of approach to delivery on these three outcomes in the Term Breech Trial were significantly different from the same rate ratios in the PREMODA study (Table 1). Nevertheless, the findings of the two studies are more similar than is generally acknowledged. For instance, the Term Breech Trial and the PREMODA study showed an almost identical ninefold excess of neonates with
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TERM BREECH TRIAL: SIGNIFICANCE OF FINDINGS WITH REGARD TO SHORT-TERM AND LONG-TERM OUTCOMES
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Table 1. Rates and Rate Ratios for Adverse Perinatal Outcomes After Planned Vaginal Delivery and Planned Cesarean Delivery in the Term Breech Trial5 and the Presentation et Mode d’Accouchement: Presentation and Mode of Delivery Study12 Term Breech Trial
Outcome Perinatal mortality or morbidity Perinatal mortality Serious neonatal morbidity Seizures 5-min Apgar score less than 4 5-min Apgar score less than 7 Birth trauma Intubation Intubation longer than 24 h NICU admission NICU admission longer than 4d
PREMODA Study Rate Ratio Planned Vaginal P for Delivery vs Difference Planned Cesarean in Rate Delivery Ratios
Planned Vaginal Delivery Rate (n51,039)
Planned Cesarean Delivery Rate (n51,039)
Rate Ratio Planned Vaginal Delivery vs Planned Cesarean Delivery
Planned Vaginal Delivery Rate (n52,502)
Planned Cesarean Delivery Rate (n55,573)
5.00
1.64
3.06 (1.78–5.25)*
1.60
1.45
1.10 (0.76–1.60)
.002
1.25
0.29
4.33 (1.24–15.2)
0.08
0.14
0.56 (0.12–2.62)
.03
3.75
1.35
2.79 (1.52–5.10)
1.52
1.31
1.16 (0.79–1.71)
.01
0.67 0.87
0.10 0.10
7.00 (0.86–56.8) 9.00 (1.14–70.9)
0.16 0.16
0.13 0.02
1.27 (0.37–4.35) 8.91 (1.00–79.7)
.14 .99
2.98
0.77
3.88 (1.79–8.39)
1.48
0.47
3.17 (1.92–5.22)
.65
1.35 1.25 0.38
0.58 0.29 0.10
2.33 (0.90–6.05) 4.33 (1.24–15.2) 4.00 (0.45–35.7)
1.80 1.04 0.40
0.47 0.57 0.38
3.86 (2.38–6.23) 1.81 (1.08–3.08) 1.06 (0.50–2.25)
.35 .19 .24
2.98
1.54
1.94 (1.07–3.52)
5.60
5.02
1.11 (0.91–1.36)
.08
0.58
0.38
1.50 (0.42–5.30)
0.92
0.95
0.97 (0.59–1.57)
.52
PREMODA, Presentation et Mode d’Accouchement: presentation and mode of delivery; NICU, neonatal intensive care unit. Data are % or rate ratio (95% confidence interval) unless otherwise specified. Bold indicates outcomes with significantly elevated and similar rate ratios in both the Term Breech Trial and the PREMODA study (ie, with nonsignificant P values for the difference in rate ratios). * This rate ratio was reported with planned cesarean delivery as the index group in the Term Breech Trial (planned cesarean delivery compared with planned vaginal delivery50.33, 95% CI 0.19–0.56).
a 5-minute Apgar score less than 4 in the planned vaginal delivery group (rate ratio [RR] 9.00, 95% confidence interval [CI] 1.14–70.9 compared with RR 8.91, 95% CI 1.00–79.7; P value for the difference in RRs 0.99). Similar and significant excess risks in the need for intubation were also seen in the planned vaginal delivery group in both studies (RR 4.33, 95% CI 1.24–15.2 and 1.81, 95% CI 1.08–3.08, respectively; P value .19). Other outcomes with significantly elevated and similar RRs in the planned vaginal delivery group in the two studies included 5-minute Apgar scores less than 7, intensive care unit admission, and birth trauma (Table 1). The difference between the Term Breech Trial and the PREMODA study with regard to perinatal
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mortality and composite perinatal mortality or morbidity may have been a consequence of the selection processes by which the index and reference groups were created in the latter study. In the Term Breech Trial, eligible women were subjected to predetermined exclusions before being randomized including (among others) fetal anomaly or other conditions, which could have caused a mechanical problem during vaginal delivery (eg, hydrocephalus) and contraindications to either labor or vaginal delivery (eg, placenta previa). On the other hand, the PREMODA trial did not use any exclusion criteria and the study included “.all women giving birth in a participating maternity unit to a singleton fetus in breech presentation at term..”12 Women in the planned cesarean
Planned Cesarean Delivery for Breech Presentation
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delivery group were identified as those who had planned to have a cesarean delivery, irrespective of whether the cesarean delivery was performed before or after labor onset or if the neonate was delivered vaginally. All other women in the study were assigned to the planned vaginal delivery group. The creation of such index and reference categories, without exclusion of women with contraindications to labor and vaginal delivery, meant that the planned cesarean delivery group likely included women with contraindications to labor and vaginal delivery who were at higher risk of adverse perinatal outcomes. Although PREMODA did exclude perinatal deaths resulting from lethal congenital anomalies and used regression adjustment to control for imbalances between groups, confounding by indication for cesarean delivery17 could not have been adequately controlled. Perhaps the most important finding of the PREMODA study is the absolute rate of perinatal death or serious neonatal morbidity (excluding deaths resulting from lethal congenital anomalies) seen in the planned vaginal group (1.60%, 95% CI 1.14–2.17).12 Women opting for a planned vaginal delivery can expect this rate of perinatal mortality or morbidity, assuming that the selection criteria and clinical expertise of the PREMODA study apply to their specific situation. However, this may be an unrealistic expectation because the availability of clinical skills required for conducting a vaginal breech delivery has declined considerably in many jurisdictions since publication of the Term Breech Trial. This is an important consideration from a pedagogic resident education and training standpoint as well. Women contemplating planned cesarean delivery can expect a composite perinatal mortality or morbidity rate of 0.53% (the previously mentioned 1.60% rate from the PREMODA study combined with the RR of 0.33 estimated by the Term Breech Trial5; Table 1). This implies a number needed to treat of 93 planned cesarean deliveries or 42 cesarean deliveries to prevent one case of perinatal death or serious neonatal morbidity (assuming a 45% compared with 90% rate of cesarean delivery among women opting for a planned vaginal compared with a planned cesarean delivery5).
both clinical equipoise and state-of-the-art expertise in administering the intervention, and monitoring of compliance with the protocol. In fact, this is exactly what was done in the Term Breech Trial with all centers representing de facto expertise in planned vaginal delivery. If the use of pelvimetry, ultrasonography, or any aspect of labor management in the Term Breech Trial fell short of expectations (as judged post hoc),18 this is not a criticism of the trial but of the state-of-the-art obstetric practice related to planned breech delivery at that time. Trials such as the Term Breech Trial5 and the more recent Twin Births Study19 represent a move toward a more rigorous evaluation of complex interventions directly relevant to clinical practice (as opposed to the evaluation of the effect of a single drug). These trials examined two distinct management algorithms, namely, planned vaginal delivery (with recourse to cesarean delivery given complications, eg, fetal distress) and planned cesarean delivery (with delivery by the vaginal route given complications, eg, precipitate labor). Trials assessing management algorithms directly relevant to clinical practice are also appearing in other specialties of medicine; the Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial20 evaluated the options for first-line antihypertensive therapy as one critical part of a multistep algorithm because hypertensive monotherapy only works in a minority of instances.
INTERNATIONAL EXPERIENCE SINCE THE TERM BREECH TRIAL
One problem with the evaluation of complex therapies is the post hoc criticism that sometimes follows an unexpected result, namely, that the complex intervention was administered imperfectly (eg, acupuncture needles were not inserted in the appropriate meridians). Avoiding such criticism requires clear, a priori specification of the intervention in the protocol, recruitment of centers with
The first national study assessing the effect of the Term Breech Trial was published from the Netherlands.21 Overall rates of cesarean delivery for breech presentation increased from 50% before the Term Breech Trial to 80% soon after. Rates of perinatal death, 5-minute Apgar score less than 7, and neonatal trauma declined in the posttrial period. These reductions were evident among those delivered by planned cesarean delivery and also among those delivered by emergency cesarean delivery and the vaginal route, leading to speculation about improved patient selection and earlier decisions to perform an emergency cesarean delivery. Nevertheless, planned vaginal delivery remained associated with significantly higher rates of perinatal death and 5-minute Apgar scores less than 7. In Denmark as well, overall rates of cesarean delivery increased in the period immediately after publication of the Term Breech Trial (from 80% to 94%).3 Significant declines were observed in rates of intrapartum and neonatal death, 5-minute Apgar score less than 7, and neonatal intensive care. Nevertheless, adverse outcome rates remained significantly higher in the planned vaginal delivery group (Table 2). Table 2
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CAN RANDOMIZED TRIALS BE USED TO EVALUATE COMPLEX THERAPIES?
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also shows data from a recent Canadian study4; adverse neonatal outcomes among women delivered vaginally were significantly higher than those among women who delivered after a cesarean without labor.
RECENT TRENDS IN PLANNED VAGINAL DELIVERY FOR BREECH PRESENTATION AT TERM AND CONCLUSION A substantial fraction of breech deliveries in the Netherlands1 and an increasing fraction of such deliveries in Canada4 are by the planned vaginal route. A recent update from the Netherlands1 estimated that
further significant reductions in perinatal mortality and morbidity could be expected if all women with breech presentation at term chose to deliver by planned cesarean. The international variations in approach to delivery and observed temporal trends are a consequence of the controversy that surrounded the Term Breech Trial, the current guidelines that suggest that planned vaginal delivery is a reasonable option,13–15 and the commitment of a segment of the population to vaginal birth. Increases in planned vaginal delivery are a healthy development insofar as they represent the evolving choices of fully informed
Table 2. Rates and Rate Ratios Expressing the Association Between Planned Vaginal Delivery Compared With Planned Cesarean Delivery and Perinatal Death and Serious Neonatal Morbidity in the Netherlands,1 Denmark,3 and Canada4 in the Postterm Breech Trial Era Planned Vaginal Delivery n
Outcome
Netherlands 2000–2007† 18,388 Perinatal death 30 5-min Apgar score less 374 than 7 Neonatal trauma 76 Perinatal death, low 424 Apgar score, or trauma 4,101 Denmark† Perinatal death 7 5-min Apgar score less 60 than 7 NICU admission 175 longer than 4 d 1,593 Canada† Neonatal death 0 Neonatal mortality or 36 serious morbidity Assisted ventilation 15 Intrapartum or birth 15 asphyxia Birth injury 20
Planned Cesarean Delivery
Rate (%)
n
Rate (%)
Rate Ratio* Planned Vaginal Delivery vs Planned Cesarean Delivery (95% CI)
Number Needed to Treat* (95% CI)
0.16 2.03
27,549 0 65
0.00 0.25
— 8.62 (6.63–11.2)
613 (—) 56 (42–75)
0.41 2.31
27 92
0.10 0.33
4.22 (2.72–6.54) 6.90 (5.52–8.64)
317 (184–593) 51 (39–66)
0.17 1.46
11,097 1 36
0.01 0.32
18.9 (2.33–153.9) 4.51 (2.99–6.81)
619 (73–8,343) 88 (53–155)
4.27
314
2.83
1.51 (1.26–1.81)
70 (44–136)
0.00 2.26
46,313 5 281
0.01 0.61
0.00 (—) 3.60 (2.52–5.15)
— 60 (38–99)
0.94 0.94
116 62
0.25 0.13
2.97 (1.72–5.13) 5.93 (3.35–10.5)
145 (88–449) 124 (79–305)
1.26
107
0.23
4.90 (3.02–7.97)
98 (63–212)
CI, confidence interval; NICU, neonatal intensive care unit. Bold indicates statistically significant differences in adverse neonatal outcomes in the planned vaginal delivery group compared with the planned cesarean delivery group. * Rate ratios for the Netherlands and Denmark were unadjusted, whereas rate ratios for Canada were adjusted for maternal age and parity. The number of cesarean deliveries required to prevent one outcome will be smaller depending on the rate of cesarean deliveries performed in the planned cesarean delivery and planned vaginal delivery groups. † Planned vaginal delivery in the Netherlands included women who had an emergency cesarean delivery and women who had a vaginal delivery, whereas planned cesarean delivery included women who had an elective cesarean delivery.1 Planned vaginal delivery in Denmark included women who delivered vaginally and those who had a cesarean delivery for labor complications, whereas planned cesarean delivery included women who had an elective cesarean delivery or a cesarean delivery during labor as a result of pregnancy complications.18 In the Canadian study, women who delivered vaginally were included in the planned vaginal delivery group and those who delivered by cesarean delivery without labor were included in the planned cesarean delivery group (a third group of women who delivered by cesarean in labor was analyzed separately).4 Composite neonatal mortality and morbidity included neonatal death, assisted ventilation, convulsions, and specific birth injury.4
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women who have the benefit of clinical expertise with regard to patient selection and labor management. Specialized clinics and clinicians experienced in vaginal delivery for breech presentation are necessary to support women who choose the vaginal option. Nevertheless, there is considerable evidence on the issue of breech delivery at term gestation and the totality of this evidence favors planned cesarean delivery as the safer option for minimizing perinatal death and serious neonatal morbidity. Health care providers should be conversant with the evidence on options for breech delivery, and women contemplating planned vaginal delivery should be fully informed about risks. REFERENCES 1. Vlemmix F, Bergenhenegouwen L, Schaaf JM, Ensing S, Rosman AN, Ravelli AC, et al. Term breech deliveries in the Netherlands: did the increased cesarean rate affect neonatal outcome? A population-based cohort study. Acta Obstet Gynecol Scand 2014;93:888–96. 2. Sullivan EA, Moran K, Chapman M. Term breech singletons and caesarean section: a population study, Australia 1991– 2005. Aust N Z J Obstet Gynaecol 2009;49:456–60. 3. Hartnack Tharin JE, Rasmussen S, Krebs L. Consequences of the term breech trial in Denmark. Acta Obstet Gynecol Scand 2011;90:767–71.
10. Kayem G, Goffinet F, Clément D, Hessabi M, Cabrol D. Breech presentation at term: morbidity and mortality according to the type of delivery at port royal maternity hospital from 1993 through 1999. Eur J Obstet Gynecol Reprod Biol 2002; 102:137–42. 11. Whyte H, Hannah ME, Saigal S, Hannah WJ, Hewson S, Amankwah K, et al. Outcomes of children at 2 years after planned cesarean birth versus planned vaginal birth for breech presentation at term: the International Randomized Term Breech Trial. Am J Obstet Gynecol 2004;191:864–71. 12. Goffinet F, Carayol M, Foidart JM, Alexander S, Uzan S, Subtil D, et al. Is planned vaginal delivery for breech presentation at term still an option? Results of an observational prospective survey in France and Belgium. Am J Obstet Gynecol 2006;194:1002–11. 13. Mode of term singleton breech delivery. ACOG Committee Opinion No. 340. American College of Obstetricians and Gynecologists. Obstet Gynecol 2006;108:235–7. 14. Royal College of Obstetricians and Gynaecologists. RCOG green top guidelines: the management of breech presentation, guideline no. 20b. London (UK): RCOG; 2006. 15. Kotaska A, Menticoglou S, Gagnon R, Farine D, Basso M, Bos H, et al. Vaginal delivery of breech presentation. J Obstet Gynaecol Can 2009;31:557–66, 567–78. 16. Joseph KS. Fetal and infant mortality and morbidity. In: Louis GB, Platt RW, editors. Reproductive and perinatal epidemiology. Oxford (UK): Oxford University Press; 2011. 17. Joseph KS, Mehrabadi A, Lisonkova S. Confounding by indication and related concepts. Curr Epidemiol Rep 2014;1:1–8.
4. Lyons J, Pressey T, Bartholomew S, Liu S, Liston R, Joseph KS. Delivery of breech presentation at term gestation, Canada, 2003 to 2011. Obstet Gynecol 2015;125:1153–61.
18. Glezerman M. Five years to the term breech trial: the rise and fall of a randomized controlled trial. Am J Obstet Gynecol 2006;194:20–5.
5. Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR. Planned cesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet 2000; 356:1375–83.
19. Barrett JF, Hannah ME, Hutton EK, Willan AR, Allen AC, Armson BA, et al. A randomized trial of planned cesarean or vaginal delivery for twin pregnancy. N Engl J Med 2013;369: 1295–305.
6. Mode of term single breech delivery. ACOG Committee Opinion No. 265. American College of Obstetricians and Gynecologists. Obstet Gynecol 2001;98:1189–90. 7. Royal College of Obstetricians and Gynaecologists. RCOG green top guidelines: the management of breech presentation, guideline no. 20. London (UK): RCOG; 2001. 8. Hellsten C, Lindqvist PG, Olofsson P. Vaginal breech delivery: is it still an option? Eur J Obstet Gynecol Reprod Biol 2003;111:122–8. 9. Giuliani A, Schöll WM, Basver A, Tamussino KF. Mode of delivery and outcome of 699 term singleton breech deliveries at a single center. Am J Obstet Gynecol 2002;187:1694–8.
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20. ALLHAT Officers and Coordinators for the ALLHAT Collaborative Research Group. The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial. Major outcomes in highrisk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) [published errata appear in JAMA 2003;289:178 and JAMA 2004;291:2196]. JAMA 2002;288: 2981–97. 21. Rietberg CC, Elferink-Stinkens PM, Visser GH. The effect of the Term Breech Trial on medical intervention behaviour and neonatal outcome in The Netherlands: an analysis of 35,453 term breech infants. BJOG 2005;112:205–9.
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Once More Unto the Breech Planned Vaginal Delivery Compared With Planned Cesarean Delivery K.S. Joseph, MD, PhD, Tracy Pressey, MD, Janet Lyons, MD, MSc, Sharon Bartholomew, Shiliang Liu, MD, PhD, Giulia Muraca, MPH, and Robert M. Liston, MB
This article provides a knowledge-based assessment of planned cesarean delivery compared with planned vaginal delivery for breech presentation at term gestation. The most critical evidence on this issue is the intention-to-treat analysis from the Term Breech Trial, which showed that planned cesarean delivery reduced composite perinatal death and serious neonatal morbidity. Although there was no difference in composite death or neurodevelopmental delay at 2 years of age, this finding was based on only 44% of randomized patients and was not an analysis by intention to treat. On the other hand, the design of the nonexperimental Presentation et Mode d’Accouchement: presentation and mode of delivery (PREMODA) study (which showed no difference in composite perinatal mortality or morbidity after planned cesarean delivery compared with planned vaginal delivery), likely favored the planned vaginal delivery group; lack of exclusion criteria led to higher risk women (with contraindications to vaginal delivery) being included in the planned cesarean delivery group. Such selection bias notwithstanding, both the Term Breech Trial and the PREMODA study showed significantly higher rates of
From the Department of Obstetrics and Gynaecology, University of British Columbia and the Children’s and Women’s Hospital and Health Centre of British Columbia, the School of Population and Public Health, University of British Columbia, Vancouver, British Columbia, and the Maternal and Infant Health Section, Public Health Agency of Canada, Ottawa, Ontario, Canada. Ms. Muraca is supported by a Vanier Canada Graduate Scholarship from the Canadian Institutes of Health Research (CIHR), and Dr. Joseph is supported by an Investigator award from the Child and Family Research Institute and a Chair in Maternal, Fetal and Infant Health Services Research from CIHR. Corresponding author: K.S. Joseph, MD, PhD, Room C403, Department of Obstetrics & Gynaecology, Women’s Hospital of British Columbia, 4500 Oak Street, Vancouver, BC, Canada V6H 3N1; e-mail: [email protected]. Financial Disclosure The authors did not report any potential conflicts of interest. © 2015 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0029-7844/15
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5-minute Apgar score less than 4, 5-minute Apgar score less than 7, intubation, and birth trauma in the planned vaginal delivery group. Finally, studies from the Netherlands, Denmark, and Canada have shown that increases in planned cesarean delivery after the Term Breech Trial led to improved neonatal outcomes. Nevertheless, planned vaginal delivery continues to be associated with higher rates of adverse perinatal outcomes in these countries. The totality of the evidence therefore unequivocally shows the relatively greater safety of planned cesarean delivery for breech presentation at term gestation. (Obstet Gynecol 2015;125:1162–7) DOI: 10.1097/AOG.0000000000000824
T
he past two decades have witnessed a substantial accumulation of evidence regarding the relative merits of different approaches to delivery for breech presentation at term gestation. However, the evolution in understanding with regard to breech delivery has been marked by controversy and some lack of clarity with regard to the merits of planned cesarean delivery compared with planned vaginal delivery. Not surprisingly, there is significant international variation in the mode of delivery for breech presentation at term.1–4 In this article, we discuss key evidentiary issues, including the effects of planned cesarean delivery compared with planned vaginal delivery on short-term compared with longer term outcomes, findings from randomized trials compared with nonexperimental studies, and a knowledge-based approach to informing and supporting women with breech presentation at term.
BREECH DELIVERY AT TERM: A BRIEF HISTORY Until the turn of the century, there was insufficient evidence favoring planned cesarean delivery or planned vaginal delivery. This situation changed with the publication of the Term Breech Trial,5 which
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showed significantly lower rates of composite perinatal mortality and serious neonatal morbidity after planned cesarean delivery compared with planned vaginal delivery. The trial led to immediate and dramatic changes in obstetric practice with the American College of Obstetrics and Gynecology6 and the Royal College of Obstetrics and Gynaecology7 issuing guidelines in 2001 recommending planned cesarean delivery for breech presentation at term. The publication of the Term Breech Trial was followed by a firestorm of criticism and several retrospective studies of planned vaginal delivery8–10 showing excellent neonatal outcomes given carefully specified protocols. The 2-year follow-up of the Term Breech Trial11 was published in 2004 and showed no difference between planned cesarean delivery and planned vaginal delivery with regard to composite death or neurodevelopmental delay. In 2006, the Presentation et Mode d’Accouchement: presentation and mode of delivery (PREMODA) study,12 a large, prospective, nonexperimental study, showed that perinatal mortality and composite perinatal mortality and serious neonatal morbidity were not significantly different between planned cesarean delivery and planned vaginal delivery groups. The alleged shortcomings of the Term Breech Trial, the demonstration of good neonatal outcomes after planned vaginal delivery with careful supervision, the lack of a difference in 2-year outcomes of the Term Breech Trial, and the negative results of the PREMODA study led to a change in attitudes within the obstetric community. In 2006, the American College of Obstetricians and Gynecologists,13 the Royal College of Obstetricians and Gynaecologists,14 and the Society of Obstetricians and Gynaecologists of Canada15 (in 2009) issued guidelines stating that the decision regarding approach to delivery “.should depend on the experience of the health care provider.”13 Whereas planned cesarean delivery remained the preferred management option, women fully informed about potential risks could reasonably be offered planned vaginal delivery with oversight from a hospital-specific protocol for eligibility and labor management.
seemingly supported by the fact that rates of perinatal death and serious neonatal mortality were significantly elevated in the planned vaginal delivery arm of the Term Breech Trial,5 whereas rates of death and neurodevelopmental delay at 2 years of age were not.11 Interpreting the results from the Term Breech Trial’s primary analysis compared with those from the 2-year follow-up requires consideration of issues related to relevance and validity.16 Clearly, the 2year outcome of composite death or neurodevelopmental delay is conceptually more relevant from a clinical and social standpoint than the immediate primary outcome of perinatal death or serious neonatal morbidity. However, from a validity standpoint, the Term Breech Trial’s contrast of death or neurodevelopmental delay at 2 years of age was compromised because this analysis was not an analysis by intention to treat. The Trial randomized 2,088 women, and information on 2,083 (99.8%) patients was available for the intention-to-treat analysis of perinatal mortality or serious neonatal morbidity.5 On the other hand, for the analysis of death or neurodevelopmental delay at 2 years of age, follow-up was planned for children from 85 of 121 centers, and of the 1,159 children from these centers, only 923 (44.2% of those randomized) were examined at 2 years of age.11 Because randomization was not stratified by center and given a greater than 50% loss postrandomization, the findings of the 2-year analysis have to be interpreted as those from a cohort study with a substantial loss to follow-up. The relatively greater relevance of the 2-year outcome notwithstanding, the only valid inference supported by the Term Breech Trial results is that perinatal mortality and serious neonatal morbidity rates are significantly reduced after planned cesarean delivery.
EVIDENCE FROM THE TERM BREECH TRIAL COMPARED WITH EVIDENCE FROM THE PREMODA STUDY
One misconception with regard to the Term Breech Trial is the belief that planned vaginal delivery increases the risk of acute, short-term outcomes but does not increase the risk of the more relevant and devastating long-term outcomes.15 This position is
The Term Breech Trial and the PREMODA study showed very different results with regard to perinatal mortality, composite perinatal mortality and neonatal morbidity, and serious neonatal morbidity. Rate ratios expressing the effect of approach to delivery on these three outcomes in the Term Breech Trial were significantly different from the same rate ratios in the PREMODA study (Table 1). Nevertheless, the findings of the two studies are more similar than is generally acknowledged. For instance, the Term Breech Trial and the PREMODA study showed an almost identical ninefold excess of neonates with
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TERM BREECH TRIAL: SIGNIFICANCE OF FINDINGS WITH REGARD TO SHORT-TERM AND LONG-TERM OUTCOMES
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Table 1. Rates and Rate Ratios for Adverse Perinatal Outcomes After Planned Vaginal Delivery and Planned Cesarean Delivery in the Term Breech Trial5 and the Presentation et Mode d’Accouchement: Presentation and Mode of Delivery Study12 Term Breech Trial
Outcome Perinatal mortality or morbidity Perinatal mortality Serious neonatal morbidity Seizures 5-min Apgar score less than 4 5-min Apgar score less than 7 Birth trauma Intubation Intubation longer than 24 h NICU admission NICU admission longer than 4d
PREMODA Study Rate Ratio Planned Vaginal P for Delivery vs Difference Planned Cesarean in Rate Delivery Ratios
Planned Vaginal Delivery Rate (n51,039)
Planned Cesarean Delivery Rate (n51,039)
Rate Ratio Planned Vaginal Delivery vs Planned Cesarean Delivery
Planned Vaginal Delivery Rate (n52,502)
Planned Cesarean Delivery Rate (n55,573)
5.00
1.64
3.06 (1.78–5.25)*
1.60
1.45
1.10 (0.76–1.60)
.002
1.25
0.29
4.33 (1.24–15.2)
0.08
0.14
0.56 (0.12–2.62)
.03
3.75
1.35
2.79 (1.52–5.10)
1.52
1.31
1.16 (0.79–1.71)
.01
0.67 0.87
0.10 0.10
7.00 (0.86–56.8) 9.00 (1.14–70.9)
0.16 0.16
0.13 0.02
1.27 (0.37–4.35) 8.91 (1.00–79.7)
.14 .99
2.98
0.77
3.88 (1.79–8.39)
1.48
0.47
3.17 (1.92–5.22)
.65
1.35 1.25 0.38
0.58 0.29 0.10
2.33 (0.90–6.05) 4.33 (1.24–15.2) 4.00 (0.45–35.7)
1.80 1.04 0.40
0.47 0.57 0.38
3.86 (2.38–6.23) 1.81 (1.08–3.08) 1.06 (0.50–2.25)
.35 .19 .24
2.98
1.54
1.94 (1.07–3.52)
5.60
5.02
1.11 (0.91–1.36)
.08
0.58
0.38
1.50 (0.42–5.30)
0.92
0.95
0.97 (0.59–1.57)
.52
PREMODA, Presentation et Mode d’Accouchement: presentation and mode of delivery; NICU, neonatal intensive care unit. Data are % or rate ratio (95% confidence interval) unless otherwise specified. Bold indicates outcomes with significantly elevated and similar rate ratios in both the Term Breech Trial and the PREMODA study (ie, with nonsignificant P values for the difference in rate ratios). * This rate ratio was reported with planned cesarean delivery as the index group in the Term Breech Trial (planned cesarean delivery compared with planned vaginal delivery50.33, 95% CI 0.19–0.56).
a 5-minute Apgar score less than 4 in the planned vaginal delivery group (rate ratio [RR] 9.00, 95% confidence interval [CI] 1.14–70.9 compared with RR 8.91, 95% CI 1.00–79.7; P value for the difference in RRs 0.99). Similar and significant excess risks in the need for intubation were also seen in the planned vaginal delivery group in both studies (RR 4.33, 95% CI 1.24–15.2 and 1.81, 95% CI 1.08–3.08, respectively; P value .19). Other outcomes with significantly elevated and similar RRs in the planned vaginal delivery group in the two studies included 5-minute Apgar scores less than 7, intensive care unit admission, and birth trauma (Table 1). The difference between the Term Breech Trial and the PREMODA study with regard to perinatal
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mortality and composite perinatal mortality or morbidity may have been a consequence of the selection processes by which the index and reference groups were created in the latter study. In the Term Breech Trial, eligible women were subjected to predetermined exclusions before being randomized including (among others) fetal anomaly or other conditions, which could have caused a mechanical problem during vaginal delivery (eg, hydrocephalus) and contraindications to either labor or vaginal delivery (eg, placenta previa). On the other hand, the PREMODA trial did not use any exclusion criteria and the study included “.all women giving birth in a participating maternity unit to a singleton fetus in breech presentation at term..”12 Women in the planned cesarean
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delivery group were identified as those who had planned to have a cesarean delivery, irrespective of whether the cesarean delivery was performed before or after labor onset or if the neonate was delivered vaginally. All other women in the study were assigned to the planned vaginal delivery group. The creation of such index and reference categories, without exclusion of women with contraindications to labor and vaginal delivery, meant that the planned cesarean delivery group likely included women with contraindications to labor and vaginal delivery who were at higher risk of adverse perinatal outcomes. Although PREMODA did exclude perinatal deaths resulting from lethal congenital anomalies and used regression adjustment to control for imbalances between groups, confounding by indication for cesarean delivery17 could not have been adequately controlled. Perhaps the most important finding of the PREMODA study is the absolute rate of perinatal death or serious neonatal morbidity (excluding deaths resulting from lethal congenital anomalies) seen in the planned vaginal group (1.60%, 95% CI 1.14–2.17).12 Women opting for a planned vaginal delivery can expect this rate of perinatal mortality or morbidity, assuming that the selection criteria and clinical expertise of the PREMODA study apply to their specific situation. However, this may be an unrealistic expectation because the availability of clinical skills required for conducting a vaginal breech delivery has declined considerably in many jurisdictions since publication of the Term Breech Trial. This is an important consideration from a pedagogic resident education and training standpoint as well. Women contemplating planned cesarean delivery can expect a composite perinatal mortality or morbidity rate of 0.53% (the previously mentioned 1.60% rate from the PREMODA study combined with the RR of 0.33 estimated by the Term Breech Trial5; Table 1). This implies a number needed to treat of 93 planned cesarean deliveries or 42 cesarean deliveries to prevent one case of perinatal death or serious neonatal morbidity (assuming a 45% compared with 90% rate of cesarean delivery among women opting for a planned vaginal compared with a planned cesarean delivery5).
both clinical equipoise and state-of-the-art expertise in administering the intervention, and monitoring of compliance with the protocol. In fact, this is exactly what was done in the Term Breech Trial with all centers representing de facto expertise in planned vaginal delivery. If the use of pelvimetry, ultrasonography, or any aspect of labor management in the Term Breech Trial fell short of expectations (as judged post hoc),18 this is not a criticism of the trial but of the state-of-the-art obstetric practice related to planned breech delivery at that time. Trials such as the Term Breech Trial5 and the more recent Twin Births Study19 represent a move toward a more rigorous evaluation of complex interventions directly relevant to clinical practice (as opposed to the evaluation of the effect of a single drug). These trials examined two distinct management algorithms, namely, planned vaginal delivery (with recourse to cesarean delivery given complications, eg, fetal distress) and planned cesarean delivery (with delivery by the vaginal route given complications, eg, precipitate labor). Trials assessing management algorithms directly relevant to clinical practice are also appearing in other specialties of medicine; the Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial20 evaluated the options for first-line antihypertensive therapy as one critical part of a multistep algorithm because hypertensive monotherapy only works in a minority of instances.
INTERNATIONAL EXPERIENCE SINCE THE TERM BREECH TRIAL
One problem with the evaluation of complex therapies is the post hoc criticism that sometimes follows an unexpected result, namely, that the complex intervention was administered imperfectly (eg, acupuncture needles were not inserted in the appropriate meridians). Avoiding such criticism requires clear, a priori specification of the intervention in the protocol, recruitment of centers with
The first national study assessing the effect of the Term Breech Trial was published from the Netherlands.21 Overall rates of cesarean delivery for breech presentation increased from 50% before the Term Breech Trial to 80% soon after. Rates of perinatal death, 5-minute Apgar score less than 7, and neonatal trauma declined in the posttrial period. These reductions were evident among those delivered by planned cesarean delivery and also among those delivered by emergency cesarean delivery and the vaginal route, leading to speculation about improved patient selection and earlier decisions to perform an emergency cesarean delivery. Nevertheless, planned vaginal delivery remained associated with significantly higher rates of perinatal death and 5-minute Apgar scores less than 7. In Denmark as well, overall rates of cesarean delivery increased in the period immediately after publication of the Term Breech Trial (from 80% to 94%).3 Significant declines were observed in rates of intrapartum and neonatal death, 5-minute Apgar score less than 7, and neonatal intensive care. Nevertheless, adverse outcome rates remained significantly higher in the planned vaginal delivery group (Table 2). Table 2
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CAN RANDOMIZED TRIALS BE USED TO EVALUATE COMPLEX THERAPIES?
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also shows data from a recent Canadian study4; adverse neonatal outcomes among women delivered vaginally were significantly higher than those among women who delivered after a cesarean without labor.
RECENT TRENDS IN PLANNED VAGINAL DELIVERY FOR BREECH PRESENTATION AT TERM AND CONCLUSION A substantial fraction of breech deliveries in the Netherlands1 and an increasing fraction of such deliveries in Canada4 are by the planned vaginal route. A recent update from the Netherlands1 estimated that
further significant reductions in perinatal mortality and morbidity could be expected if all women with breech presentation at term chose to deliver by planned cesarean. The international variations in approach to delivery and observed temporal trends are a consequence of the controversy that surrounded the Term Breech Trial, the current guidelines that suggest that planned vaginal delivery is a reasonable option,13–15 and the commitment of a segment of the population to vaginal birth. Increases in planned vaginal delivery are a healthy development insofar as they represent the evolving choices of fully informed
Table 2. Rates and Rate Ratios Expressing the Association Between Planned Vaginal Delivery Compared With Planned Cesarean Delivery and Perinatal Death and Serious Neonatal Morbidity in the Netherlands,1 Denmark,3 and Canada4 in the Postterm Breech Trial Era Planned Vaginal Delivery n
Outcome
Netherlands 2000–2007† 18,388 Perinatal death 30 5-min Apgar score less 374 than 7 Neonatal trauma 76 Perinatal death, low 424 Apgar score, or trauma 4,101 Denmark† Perinatal death 7 5-min Apgar score less 60 than 7 NICU admission 175 longer than 4 d 1,593 Canada† Neonatal death 0 Neonatal mortality or 36 serious morbidity Assisted ventilation 15 Intrapartum or birth 15 asphyxia Birth injury 20
Planned Cesarean Delivery
Rate (%)
n
Rate (%)
Rate Ratio* Planned Vaginal Delivery vs Planned Cesarean Delivery (95% CI)
Number Needed to Treat* (95% CI)
0.16 2.03
27,549 0 65
0.00 0.25
— 8.62 (6.63–11.2)
613 (—) 56 (42–75)
0.41 2.31
27 92
0.10 0.33
4.22 (2.72–6.54) 6.90 (5.52–8.64)
317 (184–593) 51 (39–66)
0.17 1.46
11,097 1 36
0.01 0.32
18.9 (2.33–153.9) 4.51 (2.99–6.81)
619 (73–8,343) 88 (53–155)
4.27
314
2.83
1.51 (1.26–1.81)
70 (44–136)
0.00 2.26
46,313 5 281
0.01 0.61
0.00 (—) 3.60 (2.52–5.15)
— 60 (38–99)
0.94 0.94
116 62
0.25 0.13
2.97 (1.72–5.13) 5.93 (3.35–10.5)
145 (88–449) 124 (79–305)
1.26
107
0.23
4.90 (3.02–7.97)
98 (63–212)
CI, confidence interval; NICU, neonatal intensive care unit. Bold indicates statistically significant differences in adverse neonatal outcomes in the planned vaginal delivery group compared with the planned cesarean delivery group. * Rate ratios for the Netherlands and Denmark were unadjusted, whereas rate ratios for Canada were adjusted for maternal age and parity. The number of cesarean deliveries required to prevent one outcome will be smaller depending on the rate of cesarean deliveries performed in the planned cesarean delivery and planned vaginal delivery groups. † Planned vaginal delivery in the Netherlands included women who had an emergency cesarean delivery and women who had a vaginal delivery, whereas planned cesarean delivery included women who had an elective cesarean delivery.1 Planned vaginal delivery in Denmark included women who delivered vaginally and those who had a cesarean delivery for labor complications, whereas planned cesarean delivery included women who had an elective cesarean delivery or a cesarean delivery during labor as a result of pregnancy complications.18 In the Canadian study, women who delivered vaginally were included in the planned vaginal delivery group and those who delivered by cesarean delivery without labor were included in the planned cesarean delivery group (a third group of women who delivered by cesarean in labor was analyzed separately).4 Composite neonatal mortality and morbidity included neonatal death, assisted ventilation, convulsions, and specific birth injury.4
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women who have the benefit of clinical expertise with regard to patient selection and labor management. Specialized clinics and clinicians experienced in vaginal delivery for breech presentation are necessary to support women who choose the vaginal option. Nevertheless, there is considerable evidence on the issue of breech delivery at term gestation and the totality of this evidence favors planned cesarean delivery as the safer option for minimizing perinatal death and serious neonatal morbidity. Health care providers should be conversant with the evidence on options for breech delivery, and women contemplating planned vaginal delivery should be fully informed about risks. REFERENCES 1. Vlemmix F, Bergenhenegouwen L, Schaaf JM, Ensing S, Rosman AN, Ravelli AC, et al. Term breech deliveries in the Netherlands: did the increased cesarean rate affect neonatal outcome? A population-based cohort study. Acta Obstet Gynecol Scand 2014;93:888–96. 2. Sullivan EA, Moran K, Chapman M. Term breech singletons and caesarean section: a population study, Australia 1991– 2005. Aust N Z J Obstet Gynaecol 2009;49:456–60. 3. Hartnack Tharin JE, Rasmussen S, Krebs L. Consequences of the term breech trial in Denmark. Acta Obstet Gynecol Scand 2011;90:767–71.
10. Kayem G, Goffinet F, Clément D, Hessabi M, Cabrol D. Breech presentation at term: morbidity and mortality according to the type of delivery at port royal maternity hospital from 1993 through 1999. Eur J Obstet Gynecol Reprod Biol 2002; 102:137–42. 11. Whyte H, Hannah ME, Saigal S, Hannah WJ, Hewson S, Amankwah K, et al. Outcomes of children at 2 years after planned cesarean birth versus planned vaginal birth for breech presentation at term: the International Randomized Term Breech Trial. Am J Obstet Gynecol 2004;191:864–71. 12. Goffinet F, Carayol M, Foidart JM, Alexander S, Uzan S, Subtil D, et al. Is planned vaginal delivery for breech presentation at term still an option? Results of an observational prospective survey in France and Belgium. Am J Obstet Gynecol 2006;194:1002–11. 13. Mode of term singleton breech delivery. ACOG Committee Opinion No. 340. American College of Obstetricians and Gynecologists. Obstet Gynecol 2006;108:235–7. 14. Royal College of Obstetricians and Gynaecologists. RCOG green top guidelines: the management of breech presentation, guideline no. 20b. London (UK): RCOG; 2006. 15. Kotaska A, Menticoglou S, Gagnon R, Farine D, Basso M, Bos H, et al. Vaginal delivery of breech presentation. J Obstet Gynaecol Can 2009;31:557–66, 567–78. 16. Joseph KS. Fetal and infant mortality and morbidity. In: Louis GB, Platt RW, editors. Reproductive and perinatal epidemiology. Oxford (UK): Oxford University Press; 2011. 17. Joseph KS, Mehrabadi A, Lisonkova S. Confounding by indication and related concepts. Curr Epidemiol Rep 2014;1:1–8.
4. Lyons J, Pressey T, Bartholomew S, Liu S, Liston R, Joseph KS. Delivery of breech presentation at term gestation, Canada, 2003 to 2011. Obstet Gynecol 2015;125:1153–61.
18. Glezerman M. Five years to the term breech trial: the rise and fall of a randomized controlled trial. Am J Obstet Gynecol 2006;194:20–5.
5. Hannah ME, Hannah WJ, Hewson SA, Hodnett ED, Saigal S, Willan AR. Planned cesarean section versus planned vaginal birth for breech presentation at term: a randomised multicentre trial. Term Breech Trial Collaborative Group. Lancet 2000; 356:1375–83.
19. Barrett JF, Hannah ME, Hutton EK, Willan AR, Allen AC, Armson BA, et al. A randomized trial of planned cesarean or vaginal delivery for twin pregnancy. N Engl J Med 2013;369: 1295–305.
6. Mode of term single breech delivery. ACOG Committee Opinion No. 265. American College of Obstetricians and Gynecologists. Obstet Gynecol 2001;98:1189–90. 7. Royal College of Obstetricians and Gynaecologists. RCOG green top guidelines: the management of breech presentation, guideline no. 20. London (UK): RCOG; 2001. 8. Hellsten C, Lindqvist PG, Olofsson P. Vaginal breech delivery: is it still an option? Eur J Obstet Gynecol Reprod Biol 2003;111:122–8. 9. Giuliani A, Schöll WM, Basver A, Tamussino KF. Mode of delivery and outcome of 699 term singleton breech deliveries at a single center. Am J Obstet Gynecol 2002;187:1694–8.
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20. ALLHAT Officers and Coordinators for the ALLHAT Collaborative Research Group. The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial. Major outcomes in highrisk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) [published errata appear in JAMA 2003;289:178 and JAMA 2004;291:2196]. JAMA 2002;288: 2981–97. 21. Rietberg CC, Elferink-Stinkens PM, Visser GH. The effect of the Term Breech Trial on medical intervention behaviour and neonatal outcome in The Netherlands: an analysis of 35,453 term breech infants. BJOG 2005;112:205–9.
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