In 1956, the cesarean delivery rate for viable, breech-presenting fetuses was 10.7%.1 The figure was low because the standard of care in the United States was to allow most gravidas carrying such fetuses a trial of labor at term. The vaginal-delivery rate did not begin to decline significantly until after 1969.
Although 2 small randomized controlled trials (RCTs) in the early 1980s found no difference in perinatal outcome between a trial of labor and elective cesarean in carefully selected breech infants at term,2,3 vaginal delivery rates continued to decrease. By 1985, only 15% of breech-presenting infants were delivered vaginally.4
When the issue of mode of delivery was examined by meta-analysis in 1995, the results indicated a higher risk of fetal injury and death in selected term breech infants after a trial of labor compared with elective cesarean.5 However, because the meta-analysis combined randomized trials and cohort studies, these findings were equivocal.
A number of retrospective, register-based studies also were published in the 1990s.6-11 Although the majority of these studies indicated a poorer outcome after vaginal breech deliveries, obstetricians did not readily accept their conclusions, since a register-based study is not able to control for many confounding variables. Indeed, because of the low incidence of breech presentations and the rarity of the outcomes taken into consideration (fetal death and significant fetal injury), it was clear that only a large, multicenter, randomized trial would help to resolve the dilemma.
—Alex C. Vidaeff, MD, and Edward R. Yeomans, MD
1. Hall JE, Kohl SC. Breech presentation: a study of 1456 cases. Am J Obstet Gynecol. 1956;72:977-990.
2. Collea JV, Chein C, Quilligan EJ. The randomized management of term frank breech presentation: a study of 208 cases. Am J Obstet Gynecol. 1980;137(2):235-244.
3. Gimovsky ML, Wallace RL, Schifrin BS, Paul RH. Randomized management of the nonfrank breech presentation at term: a preliminary report. Am J Obstet Gynecol. 1983;146(1):34-40.
4. Taffel SM, Placek PJ, Liss T. Trends in the United States cesarean section rate and reasons for the 1980-85 rise. Am J Public Health. 1987;77:955-959.
5. Gifford DS, Morton SC, Fiske M, Kahn K. A meta-analysis of infant outcomes after breech delivery. Obstet Gynecol. 1995;85(6):1047-1054.
6. Krebs L, Langhoff-Roos J, Weber T. Breech at term-mode of delivery? A register-based study. Acta Obstet Gynecol Scand. 1995;74(9):702-706.
7. Lindqvist A, Norden-Lindeberg S, Hanson U. Perinatal mortality and route of delivery in term breech presentations. Br J Obstet Gynaecol. 1997;104(11):1288-1291.
8. Koo MR, Dekker GA, van Geijn HP. Perinatal outcome of singleton term breech deliveries. Eur J Obstet Gynecol Reprod Biol. 1998;78(1):19-24.
9. Lee KS, Khoshnood B, Sriram S, et al. Relationship of cesarean delivery to lower birth weight-specific neonatal mortality in singleton breech infants in the United States. Obstet Gynecol. 1998;92(5):769-774.
10. Albrechtsen S, Rasmussen S, Dalaker K, Irgens LM. Perinatal mortality in breech presentation sibships. Obstet Gynecol. 1998;192:775-780.
11. Roman J, et al. Pregnancy outcomes by mode of delivery among term breech births: Swedish experience 1987-1993. Obstet Gynecol. 1998;92(6):945-950.
Some experienced obstetricians may claim that these findings fail to reflect their personal experience with vaginal breech delivery. Such claims demonstrate a lack of understanding of “the law of small numbers.” If the risk of perinatal death from planned vaginal birth is 1.2% (or 0.6% in countries with a low PMR), many experienced obstetricians will never see this relatively rare outcome in their personal series.
To obstetricians who feel that their own vaginal breech delivery technique would yield results more favorable to a policy of intended vaginal birth, I would issue the challenge to subject their technique to prospective, randomized comparison with elective cesarean section.
As much as it is possible for an RCT to do, the Term Breech Trial takes the “long view,” with secondary papers planned on long-term developmental outcomes in the 2 groups (up to 3 years) and long-term maternal outcomes such as incontinence and dyspareunia.
Although it fails to address the long-term implications of cesarean delivery for future reproductive risks such as uterine rupture and placenta accreta, the Term Breech Trial does yield a clear answer to the question of which treatment is better for an index pregnancy complicated by a breech presentation at term. That answer is elective cesarean delivery.
The authors report no financial relationship with any companies whose products are mentioned in this article.