No benefit, but increased harm from high dose (100 μg) misoprostol for induction of labour: a randomised trial of high vs. low (50 μg) 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 w g (low) and 100 w g (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 w g was as effective as the 100 w g dose for induction of labour whereas the higher dose had an increased risk of serious complications.