Randomized controlled trial of prolonged second stage: extending the time limit vs usual guidelines

Abstract

Background: Guidelines for management of the second stage have been proposed since the 1800s and were created largely by expert opinion. Current retrospective data are mixed regarding differences in maternal and neonatal outcomes with a prolonged second stage. There are no randomized controlled trials that have evaluated whether extending the second stage of labor beyond current American College of Obstetricians and Gynecologists recommendations is beneficial.

Objective: The purpose of this study was to evaluate whether extending the length of labor in nulliparous women with prolonged second stage affects the incidence of cesarean delivery and maternal and neonatal outcomes.

Study design: We conducted a randomized controlled trial of nulliparous women with singleton gestations at 36 0/7 to 41 6/7 weeks gestation who reached the American College of Obstetricians and Gynecologists definition of prolonged second stage of labor, which is 3 hours with epidural anesthesia or 2 hours without epidural anesthesia. Women were assigned randomly to extended labor for at least 1 additional hour, or to usual labor, which was defined as expedited delivery via cesarean or operative vaginal delivery. The exclusion criteria were intrauterine fetal death, planned cesarean delivery, age <18 years, and suspected major fetal anomaly. Primary outcome was incidence of cesarean delivery. Maternal and neonatal outcomes were compared secondarily. Statistical analysis was done by intention-to-treat.

Results: Seventy-eight nulliparous women were assigned randomly. All of the women had epidural anesthesia. Maternal demographics were not significantly different. The incidence of cesarean delivery was 19.5% (n = 8/41 deliveries) in the extended labor group and 43.2% (n = 16/37 deliveries) in the usual labor group (relative risk, 0.45; 95% confidence interval, 0.22-0.93). The number needed-to-treat to prevent 1 cesarean delivery was 4.2. There were no statistically significant differences in maternal or neonatal morbidity outcomes.

Conclusion: Extending the length of labor in nulliparous women with singleton gestations, epidural anesthesia, and prolonged second stage decreased the incidence of cesarean delivery by slightly more than one-half, compared with usual guidelines. Maternal or neonatal morbidity were not statistically different between the groups; however, our study was underpowered to detect small, but potentially clinical important, differences.

Trial registration: ClinicalTrials.gov NCT02101515.

Keywords: cesarean delivery; labor; prolonged second stage; randomized controlled trial; second stage of labor.