Effect of gestational age at the prior cesarean delivery on maternal morbidity in subsequent VBAC attempt

OBJECTIVE: The purpose of this study was to estimate the effect of gestational age at the time of prior cesarean on maternal morbidity in women attempting vaginal birth after cesarean delivery (VBAC). STUDY DESIGN: A retrospective cohort study of women attempting VBAC, comparing women with a prior cesarean delivery <= 34 completed weeks to women with a prior cesarean delivery > 34 weeks. The primary outcome was maternal morbidity, including uterine rupture. Univariable, stratified, and multivariable analyses were used to estimate the effect of a prior cesarean performed at <= 34 weeks on maternal morbidities. RESULTS: Of 19,474 women with 1 prior cesarean, 12,535 attempted VBAC and 508 of those had a previous cesarean <= 34 weeks. Study groups had similar risks of uterine rupture (adjusted OR [AOR], 1.5; 95% CI, 0.7-3.5; P = .32) and composite morbidity (AOR, 0.9; 95% CI, 0.5-1.8; P = .81). CONCLUSION: Prior cesarean delivery at <= 34 weeks' gestation does not appear to increase the risk of maternal morbidity in a subsequent VBAC attempt.