Misoprostol Vaginal Insert for Successful Labor Induction

Abstract

To compare three doses of misoprostol vaginal insert for successful labor induction measured by the proportion of vaginal deliveries within 24 hours. A total of 374 women with modified Bishop scores of 4 or lower before induction of labor were randomly assigned to receive misoprostol vaginal insert (MVI) 100 (n=118), MVI 150 (n=125), or MVI 200 (n=131) micrograms. The insert was removed for onset of active labor or adverse event. The primary outcome was proportion of vaginal deliveries within 24 hours. The comparison group was MVI 100. Safety was assessed by comparing rates of cesarean deliveries and adverse events. Twenty-four percent of women receiving MVI 200 failed to achieve vaginal delivery within 24 hours compared with 36.3% of those receiving MVI 100 (P=.057, relative risk [RR] 0.66, 95% confidence interval [CI] 0.42-1.04). Compared with MVI 100, MVI 200 reduced median time to vaginal delivery (1,181 compared with 1,744 minutes, P=.02) and need for oxytocin (48.9% compared with 70.9%, P<.001, RR 0.70, 95% CI 0.56-0.85). The cesarean rates for women assigned to MVI 200 and 100 were 22.9% (30/131) and 31.4% (37/118) (P=.15, RR 0.73, 95% CI 0.48-1.10). Misoprostol vaginal insert 200 was associated with an increased rate of tachysystole (41.2%) compared with MVI 100 (19.5%) (P<.001, RR 2.11, 95% CI 1.39-3.22). Compared with MVI 100, MVI 200 was associated with a significant reduction in time to vaginal delivery, but did not improve proportion with vaginal delivery by 24 hours. ClinicalTrials.gov, www.clinicaltrials.gov, NCT00828711.