Propranolol does not reduce cesarean delivery in prolonged labor

Researchers observed no differences in rates of cesarean delivery among women with prolonged labor who were administered propranolol vs. placebo, findings presented at The Pregnancy Meeting showed.

“Propranolol has compelling biologic plausibility for a role in labor management, and it is currently used by some providers as a treatment for labor arrest,” Jennifer A. McCoy, MD, MSCE, assistant professor of OB/GYN at the Hospital of the University of Pennsylvania in Philadelphia, told Healio. “But, it needed more study to determine if it was truly effective for use in labor.”

McCoy and colleagues enrolled 164 women aged 16 years or older who were 36 or more weeks pregnant and who were in prolonged latent or active labor. Participants were randomly assigned to IV propranolol hydrochloride 2 mg (n = 84) or IV placebo 2 mg (n = 80), which was readministered once if dilation changed by less than 2 cm over more than 2 hours.

The primary outcome was mode of delivery, with secondary outcomes including duration of labor and second stage of labor, time to delivery after propranolol or placebo, amount of oxytocin administered and maternal and neonatal morbidity.

Rates of cesarean delivery were similar between the propranolol and placebo groups (57% vs. 58%), with no significant differences by parity or by enrollment during active or latent labor. In both groups, a similar proportion of participants received two doses.

Additionally, length of labor and each phase of labor were similar between participants assigned to propranolol vs. placebo. Both groups received similar doses of oxytocin.

There were no differences in composite maternal morbidity in the propranolol vs. placebo group. Although the P value for postpartum hemorrhage did not reach significance, adjusted analyses revealed propranolol was associated with a greater risk for postpartum hemorrhage vs. placebo (adjusted OR = 2.79; 95% CI, 1.06-7.33). This indicates that propranolol may increase the risk for postpartum hemorrhage.

For neonatal outcomes, neonates in the propranolol group had heavier birth weights vs. the placebo group (median, 3,515 g vs. median, 3,333 g; P = .02). Other outcomes were not significant.

“Our findings show that providers should not use propranolol for the management of prolonged labor, but should instead focus on fully utilizing oxytocin and other strategies for labor augmentation that we know work,” McCoy said.

Moving forward, McCoy expressed interest in improving the management of prolonged labor.