BACKGROUND: Based on data from a large randomized controlled trial on the management of women with prelabor rupture of membranes (PROM) at term (the TermPROM Study), planned induction of labor (IOL) with oxytocin, when compared to planned expectant management, may decrease the rate of maternal infection but does not affect the risk of neonatal infection and cesarean delivery (CD). However, the original analysis did not assess the PROM-to-induction interval in a continuous manner. Therefore, the optimal timing of IOL remains to be determined. To investigate the association between PROM-to-induction interval and maternal and neonatal outcomes in women with term PROM. METHODS: A cohort study design based on data from the TermPROM trial. At each interval from onset of PROM, maternal and neonatal outcomes were compared between women who underwent IOL and those managed expectantly at this interval. Neonatal outcomes included a composite of probable or definite neonatal infection and admission to neonatal intensive care unit (NICU). Maternal outcomes included a composite of maternal infection (chorioamnionitis or postpartum fever) and CD. A total of 4,564 of the 5,041 women included in the original trial met study criteria. The rate of neonatal infection was low overall (3.3±1.1%), increased with the interval from PROM but was not different between IOL vs. expectant management at any interval (Figure 1). The rate of NICU admission increased with the interval from PROM and was significantly lower among women undergoing IOL compared with expectant management at any given interval within the first 13 hours from PROM (Figure 1). Among women who underwent IOL within the first 15 hours after PROM the rate of maternal infection remained stable at approximately 6% and was significantly lower than in women managed expectantly during this time period (Figure 1). The rate of CD was not affected by the interval from PROM or by IOL (Figure 1). The proportion of women who experienced spontaneous labor increased with the interval from PROM increasing to 40% at 15 hours after PROM (Figure 2). CONCLUSIONS: In women with term PROM, immediate IOL can minimize the risk of maternal infection and NICU admission. However, delaying induction by up to 15 hours may allow for up to 40% of women to go into spontaneous labor without increasing the risk of infection or CD, but at the price of increased risk of NICU admission.View Large Image Figure ViewerDownload Hi-res image Download (PPT)