Oral or Vaginal Misoprostol for Labor Induction and Cesarean Delivery Risk

OBJECTIVE: To evaluate whether cervical ripening with oral misoprostol increases cesarean delivery risk and prolongs time to vaginal delivery compared with vaginal misoprostol in a predominantly overweight population. METHODS: This single center, retrospective cohort study was performed at a tertiary care academic medical center and compared labor induction outcomes with vaginal misoprostol to outcomes with oral misoprostol after a complete institutional shift to oral misoprostol. Labor induction using 25 micrograms vaginal misoprostol in 20132014 was compared with 50 micrograms oral misoprostol in 2014-2015. The primary outcome was cesarean delivery. Secondary outcomes included time to vaginal delivery, uterine tachysystole, maternal hemorrhage, and composite adverse neonatal outcomes. Demographics and outcomes were analyzed using standard statistical tests. Multivariable regression models accounting for potential confounders were created for the primary and secondary outcomes with adjusted odds ratios (aOR) as the measures of effect. RESULTS: There were 138 women in the oral and 138 women in the vaginal misoprostol groups. In the overall cohort, the median (interquartile range) body mass index was 31.7 (28.2-36.8) and most women (72%) were of either black or Hispanic race or ethnicity. The frequency of cesarean delivery was higher in the oral than the vaginal misoprostol group (32% vs 21%; P=.04). The adjusted odds of cesarean was higher with oral misoprostol (aOR 2.01; 95% CI 1.07-3.76). Among nulliparous women, the frequency of cesarean delivery was 41% in the oral and 28% in the vaginal misoprostol groups (aOR 2.79; 95% CI 1.26-6.19). Women had a longer time to vaginal delivery in the oral compared with vaginal misoprostol group (41 vs 31 hours respectively, P=.01). Tachysystole occurred more frequently with vaginal misoprostol (20% vs 11%; P=.04). CONCLUSION: Compared with vaginal misoprostol, oral misoprostol may be associated with increased risk of cesarean delivery and longer time to vaginal delivery.