364: Length of the second stage of labor in nulliparas in a contemporary US hospital population

Abstract

To evaluate the duration of the second stage of labor in nulliparous singleton deliveries with and without epidural. Retrospective cohort study using data from a multicenter quality improvement program based in Washington State. Nineteen hospitals participating in the program for all or part of the study period were included. The study cohort was restricted to singleton deliveries at 37+0-42+6 weeks of gestation between Jan 1, 2012 and Dec 31, 2016. Exclusion criteria were antepartum stillbirth, fetal anomalies, missing data for mode of delivery or cervical dilation at cesarean. Those with unknown duration of the second stage or second stage >12 hours were also excluded. Median and 95th percentiles for the length of the second stage were calculated for spontaneous vaginal, operative vaginal, and second stage cesareans. Length of the second stage was compared using the Kruskal-Wallis test. Of the 91353 term deliveries during the study period, 32837 were singletons with no exclusion criteria. Ninety-two percent (n=30327) attempted a vaginal delivery, of whom 84.6% (n=25655) reached the second stage Duration of the second stage of labor was available for 25241 (19740 spontaneous vaginal, 3311 operative vaginal, and 2190 cesarean deliveries). The length of the second stage of labor was significantly longer in those with epidurals (P<0.01). The median and 95th percentile for the length of the second stage were 1.9 hours and 5.6 hours respectively in those with an epidural, and 42 minutes and 3.4 hours respectively in those without an epidural (Table). Using previously suggested criteria for prolonged second stage, of those delivering vaginally (spontaneous/operative vaginal delivery), 11.9% (n=2143) of those with an epidural had a second stage >4 hours and 6.0% (307) of those without an epidural had a second stage >3 hours. This cohort of nulliparous singleton term deliveries demonstrates an approximately two-fold increase in the median duration of the second stage and a 2 hour increase in the 95th percentile in those with epidurals. Less restrictive guidelines on second stage duration for nulliparas with epidurals may increase vaginal delivery rates. However, more information is needed to determine when the benefits of continuing in the second stage are outweighed by low likelihood of vaginal delivery and increased risks for adverse outcomes.