Efficacy of 50 µg Versus 25 µg Vaginal Misoprostol for Cervical Ripening and Labor Induction: A Randomized Trial

Abstract

Background: Cervical ripening is the process of initiating labor in women with an unripe cervix. Vaginally administered prostaglandin E1 analog (misoprostol) has been promising in cervical ripening and labor induction. However, optimal dosage and dose-dependent adverse effects in this administration route need further clarification. Objectives: This trial aimed to compare the efficacy and adverse effects of 50 mcg vs. 25 mcg of vaginal misoprostol in low-risk term pregnant women. Methods: This double-blind, single-center, randomized clinical trial included 200 low-risk term pregnancies undergoing labor induction with a Bishop score of 2 or less. Patients were assigned randomly to receive 25 mcg or 50 mcg of vaginal misoprostol every six hours up to four times until the active phase of labor was reached. The primary outcome included time to vaginal delivery (latent and active phase of labor), and secondary outcomes included the total dosage of prescribed misoprostol, the need for oxytocin for labor augmentation, and the cesarean section rate. Results: Misoprostol 50 micrograms resulted in a significantly shorter time in the first phase of labor (P-value = 0.002), the second phase of labor (P-value = 0.030), and the third phase of labor (P-value = 0.020). The number of administered misoprostol, the need for additional oxytocin, uterine hyperstimulation, cesarean delivery rate, Apgar score, umbilical artery pH, and neonatal intensive care unit (NICU) administration were statistically similar between the two groups. Conclusions: This study showed that 50 mcg of vaginal misoprostol (vs. 25 mcg) for cervical ripening could reduce labor phase duration without significantly increasing adverse maternal and neonatal outcomes.