Outcomes of Term Induction in Trial of Labor After Cesarean Delivery: Analysis of a Modern Obstetric Cohort.

OBJECTIVE To evaluate outcomes of induction of labor, compared with expectant management, in women attempting trial of labor after cesarean delivery (TOLAC) in a large obstetric cohort. METHODS We performed a secondary analysis of data from the Consortium on Safe Labor that included women with term (37 weeks of gestation or greater) singleton gestations and a history of one prior cesarean delivery who attempted TOLAC. Induction of labor was compared with expectant management by week of gestation from 37 to 40 weeks in both high- and low-risk cohorts. The primary outcome was failed TOLAC. Secondary outcomes included composite maternal morbidity (hysterectomy, transfusion, intensive care unit (ICU) transfer, venous thromboembolism, death), composite neonatal morbidity (5-minute Apgar score less than 5, cord pH less than 7.0, asphyxia, hypoxic ischemic encephalopathy, neonatal death), and neonatal ICU admission. Multivariate logistic regression was performed with adjustment for confounding factors. RESULTS We identified 6,033 women attempting TOLAC of whom 1,626 (27.0%) underwent induction of labor and 4,407 (73.0%) did not. Compared with expectant management, induction was associated with an increased risk of failed TOLAC at 37-39 weeks of gestation but not at 40 weeks of gestation (37 weeks of gestation, 48.5% compared with 34.3%, adjusted odds ratio [OR] 1.53, 95% confidence interval [CI] 1.02-2.28]; 38 weeks of gestation, 47.0% compared with 33.0%, adjusted OR 1.74, 95% CI 1.29-2.34; 39 weeks of gestation, 45.6% compared with 29.8%, adjusted OR 2.16, 95% CI 1.76-2.67; 40 weeks of gestation, 37.9% compared with 29.4%, adjusted OR 1.21, 95% CI 0.90-1.66). Induction was associated with an increased risk of composite maternal morbidity at 39 weeks of gestation (adjusted OR 1.87, 95% CI 1.22-2.87) and neonatal ICU admission at 37 weeks of gestation (adjusted OR 2.51, 95% CI 1.62-3.90). Induction was not associated with an increased risk of neonatal morbidity. CONCLUSION Induction of labor in women with one prior cesarean delivery, compared with expectant management, is associated with an increased risk of failed TOLAC. Apart from small increases in maternal morbidity at 39 weeks and neonatal ICU admission at 37 weeks of gestation, induction is not associated with an increased risk of severe maternal or neonatal morbidity. LEVEL OF EVIDENCE II.