Vaginal birth after cesarean (VBAC) outcomes associated with increasing number of prior VBACs.

Evaluation of: Mercer BM, Gilbert S, Landon MB et al., for the National Institute of Child Health and Human Development Maternal-Fetal medicine Units Network: Labor outcomes with increasing number of prior vaginal births after cesarean delivery. Obstet. Gynecol. 111(2), 285-291 (2008). From a prospective US multicenter cohort of 45,988 patients with a singleton gestation and a prior cesarean, 13,532 women that elected to attempt a vaginal birth after cesarean (VBAC) were selected for this secondary analysis. This study was conducted to estimate the success rates and risks of an attempted VBAC according to the number of previously successful VBAC attempts. Outcomes evaluated included VBAC success, maternal major morbidity (e.g., uterine rupture and surgical complications), neonatal morbidity (e.g., intensive care nursery admission and acidemia) and maternal and neonatal death. The VBAC success rate rose incrementally from 63.3 to 91.6% in patients that had from zero to four or more prior successful VBACs. Uterine rupture and peripartum risks decreased by 50% after the initial successful VBAC and did not increase with increasing prior VBAC number. Neonatal morbidity did not increase with increasing VBAC number.