Comparative efficacy and safety of vaginal misoprostol versus dinoprostone vaginal insert in labor induction at term: a randomized trial

Objective  To compare efficacy and safety of vaginal misoprostol (PGE₁ analog) with dinoprostone (PGE₂ analog) vaginal insert for labor induction in term pregnancies. Study design  A total of 112 women with singleton pregnancies of ≥37 weeks of gestation, and low Bishop scores underwent labor induction. The subjects were randomized to receive either 50 μg misoprostol intravaginally every 4 h to a maximum of five doses or a 10 mg dinoprostone vaginal insert for a maximum of 12 h. Time interval from induction to vaginal delivery, vaginal delivery rates within 12 and 24 h, requirement of oxytocin augmentation, incidence of tachysystole and uterine hyperstimulation, mode of delivery, rate of cesarean section due to fetal distress and neonatal outcome were outcome measures. Student’s t test, Chi square test, Fischer’s exact test were used for statistical analysis. Results  Time interval from induction to vaginal delivery was found to be significantly shorter in misoprostol group when compared to dinoprostone subjects (680 ± 329 min vs. 1070 ± 435 min, P < 0.001). Vaginal delivery rates within 12 h were found to be significantly higher with misoprostol induction [n = 37 (66%) vs. n = 25 (44.6%); P = 0.02], whereas vaginal delivery rates in 24 h did not differ significantly between groups [n = 41 (73.2%) vs. n = 36 (64.2%); P = 0.3]. More subjects required oxytocin augmentation in dinoprostone group [n = 35 (62.5%) vs. n = 20 (35.7%), P = 0.005] and cardiotocography tracings revealed early decelerations occurring more frequently with misoprostol induction (10.7 vs. 0%, P = 0.03). Tachysystole and uterine hyperstimulation, mode of delivery, rate of cesarean sections due to fetal distress and adverse neonatal outcome were not demonstrated to be significantly different between groups (P = 1, P = 0.5, P = 0.4, P = 0.22, P = 0.5). Conclusion  Using vaginal misoprostol is an effective way of labor induction in term pregnant women with unfavorable cervices, since it is associated with a shorter duration of labor induction and higher rates of vaginal delivery within 12 h. Misoprostol and dinoprostone are equally safe, since misoprostol did not result in a rise in maternal and neonatal morbidity, namely, tachysystole, uterine hyperstimulation, cesarean section rates and admission to neonatal intensive care units as reported previously in literature.