Objective: To examine the population-based pregnancy outcomes associated with vaginal breech delivery.
Methods: A retrospective, population-based cohort study of all term (greater than 37 weeks' gestation), normal birth weight (2.5-3.8 kg), nonanomalous newborns in California, from January 1, 1991 to December 31, 1999 was performed. Neonatal mortality and major neonatal morbidity were compared by route of delivery for cephalic (3,271,092) and breech (100,730) presentations.
Results: More than 3.2 million singleton term newborns were identified during the study period, with 100,667 (3%) in breech presentation at the time of delivery. Of these, 4952 women (4.9%) had vaginal breech delivery, whereas 60,418 women delivered by cesarean without labor, and 35,297 women underwent cesarean in labor. Breech vaginal delivery in nulliparous women was associated with increased neonatal mortality (odds ratio [OR] 9.2, 95% confidence interval [CI] 3.3, 25.6) and morbidity (asphyxia: OR 5.7, 95% CI 4.5, 7.3; brachial plexus injury: OR 33.9, 95% CI 15.2, 76.1; and birth trauma: OR 5.8, 95% CI 4.7, 7.1) compared with breech delivery by prelabor cesarean in nulliparous women. In breech-presenting women with one prior vaginal delivery, neonatal mortality was not different between groups, but morbidities (asphyxia: OR 3.9, 95% CI 3.0, 5.1; brachial plexus injury: OR 22.4, 95% CI 9.9, 50.5; and birth trauma: OR 4.2, 95% CI 3.4, 5.3) remained increased for vaginal compared with cesarean delivery.
Conclusion: The "normal" term breech fetus, when delivered vaginally, had significantly increased neonatal mortality (in nulliparous women) and morbidity (all breech deliveries), when compared with the breech fetus delivered by cesarean, which suggests that these patients might best be delivered by cesarean to avoid these adverse outcomes.