Labor induction with 25 microg versus 50 microg intravaginal misoprostol: a systematic review

To systematically review published randomized controlled trials (RCTs) to compare the safety and efficacy of 25 microg versus 50 microg of intravaginal misoprostol for cervical ripening and labor induction.

We supplemented a search of entries in electronic databases with references cited in original studies and review articles to identify RCTs of misoprostol for cervical ripening and labor induction, which compared repeated doses of 25 microg and 50 microg.

We evaluated, abstracted data, and assessed the quality of RCTs to compare the safety and efficacy of 25 microg versus 50 microg of intravaginal misoprostol for cervical ripening and labor induction.

Five RCTs met inclusion criteria for meta-analysis. Odds ratios (OR) with 95% confidence intervals (CI) were calculated for each outcome (random- and fixed-effects models). In addition, we aggregated the results of two separate studies, permitting an indirect comparison of the two doses being analyzed. In the meta-analysis, tachysystole and hyperstimulation syndrome appear to occur less frequently among women who received 25 microg of misoprostol than with 50 microg. However, neonatal outcomes appear to be comparable with the two doses. Regarding efficacy, use of the 50-microg dose was associated with a shorter interval to vaginal delivery, greater proportion of deliveries within 24 hours, and less frequent need for oxytocin augmentation. The indirect comparison of two studies yielded similar results.

Published data indicate that intravaginal misoprostol at doses of 50 microg for cervical ripening and labor induction is more efficacious but it is unclear whether it is as safe as the 25-microg dose.