Induction of Labor in Post-Term Nulliparous and Parous Women - Potential Advantages of Misoprostol over Dinoprostone.

Abstract

We undertook a prospective cohort study to compare the effectiveness and safety of 50 µg misoprostol versus 3 mg dinoprostone in two vaginal doses 6 hours apart, followed if necessary by oxytocin for labor induction in low-risk post-term (> 40 weeks) pregnancies with unfavorable cervix (Bishop score ≤ 6). Labor induction and subsequent management were conducted using a standardized protocol. The primary outcome of the study was labor induction rate. Secondary outcomes included mode of delivery, time interval from induction to delivery, maternal complications and neonatal outcome. 107 patients received misoprostol (Group A) and 99 patients received dinoprostone (Group B). Compared with group A, more women in Group B needed a second vaginal dose of prostaglandin or oxytocin infusion in order to proceed to labor (21.5 vs. 43.4 %; p = 0.01). Misoprostol alone as a single or double vaginal dose was more effective than dinoprostone alone in inducing labor without oxytocin administration (85.0 vs. 50.4 %; p = 0.04). Overall, the rate of successful induction of labor did not differ between groups (91.6 vs. 85.8 %; p = 0.75). Vaginal delivery, operative vaginal delivery and Caesarean section rates were not significantly different. Time interval from induction to delivery however, was shorter for Group A (median 11 hours vs. 14.1 hours; p < 0.001). Though emergency Caesarean section due to fetal distress was more frequent in Group A (16.8 vs. 4.0 %; p = 0.007), low Apgar scores < 7 and NICU admissions did not differ significantly. Maternal complications, mostly not serious, were higher in Group A (31.8 vs. 2.0, p < 0.001). Misoprostol is a more effective agent than dinoprost in post-term pregnancy for labor induction with few maternal adverse effects.