No benefit, but increased harm from high dose (100 microg) misoprostol for induction of labour: a randomised trial of high vs. low (50 microg) dose misoprostol

Abstract

Misoprostrol, a synthetic analogue of prostaglandin E(1), has been used for cervical preparation. Its ideal dose, route and frequency of administration are still under investigation. We conducted a randomised controlled trial, in a tertiary hospital in a developing country, to compare misoprostol 50 microg (low) and 100 microg (high) for effectiveness and safety in induction of labour at term. Women admitted for induction of labour with a singleton live fetus in cephalic presentation after 37 weeks' gestation were recruited. A misoprostol tablet was inserted in the posterior vaginal fornix at 8-hour intervals. Main outcomes were duration of induction, maternal and fetal complications. The mean duration of induction was 15.4 (SD 10.6) and 14.2 (SD 13.6) h in the low- and high-groups respectively (P = 0.095). There was no difference in need for augmentation with oxytocin (OR 0.82; 95% Cl 0.36-1.86) or operative delivery (OR 1.29; 95% CI 0.26-6.84). There were two uterine ruptures and four intrapartum stillbirths in the high misoprostol group. There was no difference in postpartum haemorrhage, 9.5% vs. 7.9% (P = 1.00) and admissions to the neonatal unit 18.8% vs. 17.0% (P = 0.980) in the 1ow- and high-groups) respectively. Misoprostol 50 microg was as effective as the 100 microg dose for induction of labour whereas the higher dose had an increased risk of serious complications.