A randomized controlled trial of propranolol in nulliparous patients with prolonged labor

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.

An open-label randomized clinical trial was conducted from July 2019 through June 2022 comparing 2mg of intravenous propranolol administration to usual care 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.

80 nulliparous participants (40 propranolol, 40 usual care) were randomized. Propranolol administration did not achieve a significantly faster median time to delivery compared to usual care, (propranolol: 27.7 hrs vs. usual care: 30.4 hrs, P<.52). Equal proportions of individuals delivered vaginally within 24hrs of randomization (propranolol: 27.5% vs. usual care: 27.5%, P<1.0). There was no difference in the cesarean delivery rate between the 2 groups (57.5% versus 55.0%, P=1.0) and no difference in time to active labor (propranolol: 19.5 hrs vs. usual care: 26.0 hrs, P<.22). There were no significant differences in maternal and neonatal outcomes.

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 latent labor in nulliparous patients undergoing IOL at term.