Addition of isosorbide mononitrate to misoprostol for cervical ripening in post-term pregnancy: A randomized controlled trial

Abstract

ObjectiveThe purpose of this paper is to compare the effect of vaginal isosorbide mononitrate added to misoprostol versus misoprostol alone in cervical ripening and labor induction in post-term pregnancy. MethodsIn this double-blind controlled trial study, 150 pregnant women in post-term pregnancy who were candidates for labor induction were selected. The participants were assigned randomly to receive either vaginal isosorbide mononitrate (IMN) (40mg) or placebo. Misoprostol (25mg) was added to both groups as needed. Time to full cervical ripening, time to delivery, and the amount of misoprostol used in each group were assessed. ResultsThe time interval from the administration of IMN to full cervical ripening was shown to be significantly lower in the IMN+ misoprostol groups versus the comparison group (p=.032). The adjusted analysis of this time interval after controlling for age, BMI, gravidity, and Bishop score on administration remained significantly less (p=.045),the mean difference being −4.85h, CI 95% −9.58 to −.12. Isosorbide treatment resulted in significantly less misoprostol used versus misoprostol alone (2.37±1.02 versus 3.08±1.29), adjusted p-value=.001, CI 95% −1.09 to −.32. We found no significant increase in maternal–fetal outcomes or side effects of the IMN+ misoprostol group compared with the misoprostol group. ConclusionThis study found that intravaginal IMN added to misoprostol is more effective in reducing time to full cervical ripening versus misoprostol alone in post-term pregnancy. It also reduces the need for more misoprostol.