A Randomized Controlled Trial of Propranolol in Nulliparous Patients with Prolonged Labor: The PROLABOR Trial

Propranolol use has been proposed to shorten the length of labor following prolonged induction. We sought to determine if administration of propranolol reduces the duration of labor among nulliparous individuals with prolonged latent labor following induction (IOL) at term. A randomized clinical trial was conducted from July 2019 through June 2022 comparing 2mg of intravenous propranolol administration to expectant management for prolonged latent labor. Nulliparous individuals undergoing IOL at ≥37 weeks with a singleton gestation and cervical dilation ≤2cm were included. Prolonged latent labor was defined as no cervical change ≥8 hours with ruptured membranes and receiving oxytocin. Labor management was standardized among participants. Our primary outcome was time to delivery. Kruskal-Wallis, Pearson chi-square and Cox regression analyses with intent-to-treat principles were performed. 80 nulliparous participants (40 propranolol, 40 expectant management) were randomized. Propranolol administration did not achieve a faster median time to delivery compared to expectant management, (Propranolol: 27.7 hrs vs. Expectant management: 30.4 hrs, p< 0.52). Equal proportion of individuals delivered vaginally within 24hrs (Propranolol: 27.5% vs. Expectant management: 27.5%, p< 1.0). There was no difference in the cesarean delivery rate between the two groups (57.5% versus 55.0%, p=1.0) and no difference in time to active labor (Propranolol: 19.5 hrs vs. Expectant management: 26.0 hrs, p< 0.22). There were no significant differences in maternal and neonatal outcomes. We found that propranolol administration did not shorten the time to delivery or increase vaginal delivery in nulliparous individuals with a prolonged latent labor course. Our findings do not support the use of propranolol for prolonged labor in nulliparous patients undergoing IOL at term.View Large Image Figure ViewerDownload Hi-res image Download (PPT)