Balancing the efficacy and safety of misoprostol: a meta-analysis comparing 25 versus 50 micrograms of intravaginal misoprostol for the induction of labour.

Abstract

The optimal dose of misoprostol for the induction of labour remains uncertain. To compare the efficacy and safety of 25 versus 50 micrograms of intravaginal misoprostol tablets for the induction of labour and cervical ripening. We performed electronic and manual searches to identify relevant randomised trials. The efficacy outcomes assessed were rates of vaginal delivery within 24 hours, delivery within one dose, and oxytocin augmentation, and interval to delivery. The safety outcomes assessed were incidences of tachysystole, hyperstimulation, caesarean delivery, cesarean delivery for non-reassuring fetal heart rate (FHR), operative vaginal delivery, abnormal 5-minute Apgar score, abnormal cord gas values, admission to a neonatal intensive care unit (NICU), and meconium passage. Thirteen studies (1945 women) were included. Relative risk (RR) and 95% confidence intervals (CI) were calculated using fixed-effects and random-effects models. We found that 25 micrograms was less efficacious, with lower rates of delivery after one dose (RR 0.59; 95% CI 0.39-0.88) and vaginal delivery within 24 hours (RR 0.88; 95% CI 0.79-0.96), and with increased rates of oxytocin augmentation (RR 1.54, 95% CI 1.36-1.75). We noted an improved safety profile with 25 micrograms, however, with decreased rates of tachysystole (RR 0.46; 95% CI 0.35-0.61), hyperstimulation (RR 0.5; 95% CI 0.31-0.78), caesarean deliveries for non-reassuring FHR (RR 0.67; 95% CI 0.52-0.87), NICU admissions (RR 0.63; 95% CI 0.4-0.98), and meconium passage (RR 0.65; 95% CI 0.45-0.96). Although 50 micrograms of intravaginal misoprostol may be more efficacious, safety concerns make the 25-microgram dose preferable.