389: Early amniotomy for indicated induction of labor in late preterm gestations

Abstract

Current evidence, including a randomized controlled trial, suggest that early amniotomy (EA) during term induction of labor (IOL) decreases length of labor without increasing neonatal or maternal morbidity. It remains unclear whether this strategy applies to those delivered in the late preterm period. Our objective is to determine the efficacy and safety of EA for indicated IOL in this cohort. This is a secondary analysis of a multi-center randomized trial on antenatal late preterm steroids to improve neonatal respiratory morbidity. All women with singleton pregnancies undergoing indicated IOL at 34 0/7 - 36 6/7 weeks gestation were considered for analysis. EA was defined as artificial rupture of membranes within 5 hours of starting IOL. All patients that did not undergo EA were considered to have late amniotomy (LA, whether artificial or spontaneous). Pregnancies with major fetal anomalies, placenta previa/abruption, PPROM or preterm labor, cervical dilation > 4 cm and spontaneous rupture prior to 5 hours after starting IOL were excluded. Women that had EA were compared to those that had LA. The primary outcome was cesarean delivery. Secondary outcomes were rates of continued pregnancy after 24 hours on oxytocin after amniotomy, composite neonatal morbidity (defined in Table 1), and chorioamnionitis/endometritis. Logistic regression models were fit to determine adjusted odds ratios (aOR) with 95% confidence intervals (CI) for each outcome. Of the 775 women meeting inclusion criteria, 177 (22.8%) underwent EA and 598 (77.2%) had LA. Relevant baseline clinical characteristics and outcomes by univariate analysis are shown in Table 1. The rate of cesarean delivery was significantly lower in the EA group (16.4% vs. 31.8%, aOR 0.53; 95% CI 0.34-0.83). There was no difference in the rate of continued pregnancy after 24 hours on oxytocin with ruptured membranes. In addition, aORs for composite neonatal morbidity and intrauterine infection were not significantly different (Table 2). Early amniotomy during induction of labor in the late preterm period is associated with a decreased rate of cesarean delivery without increasing the risk of either maternal infection or neonatal morbidity.View Large Image Figure ViewerDownload Hi-res image Download (PPT)