Induction of labor versus expectant management in patients with idiopathic polyhydramnios

Objective: To evaluate whether induction of labor is associated with lower risk of cesarean section compared to expectant management in patients with isolated polyhydramnios. Study Design: This is a single-center, retrospective cohort study of patients with pregnancies complicated by idiopathic polyhydramnios, documented between 34 and 38 weeks gestation, who were delivered between July 2012 and February 2020. The primary outcome was cesarean delivery. Secondary outcomes included chorioamnionitis, endometritis, postpartum hemorrhage, preeclampsia/gestational hypertension, and composite neonatal morbidity. Results: There were 194 patients included with idiopathic polyhydramnios – 115 underwent induction and 79 patients were expectantly managed. Planned induction was associated with a lower rate of CD compared with expectant management but did not meet statistical significance (19.1 % vs 30.4 %, aOR 0.51, 95 % CI 0.24, 1.05). A similar effect was seen when stratifying for parity: both nulliparous (9.1 % vs 16.3 %, aOR 0.59, 95 % CI 0.17, 1.98) and multiparous (32.7 % vs 47.2 %, aOR 0.45, 95 % CI 0.18, 1.15) patients had a lower CD rate when there was a planned induction, though neither group met statistical significance. No differences in maternal or fetal secondary outcomes were identified (chorioamnionitis, endometritis, postpartum hemorrhage, preeclampsia/gestational hypertension, composite neonatal morbidity). Conclusion: Lower rates of cesarean section were associated with labor induction for patients with isolated polyhydramnios, but confidence intervals did not reach statistical significance.