Labour characteristics and uterine activity: misoprostol compared with oxytocin in women at term with prelabour rupture of the membranes

Objective To compare the labour pattern and uterine activity of oral misopr ostol with oxytocin for labour induction in women presenting with prelabour rupture: of membranes at term. Design Prospective randomised study. Setting Department of Obstetrics and Gynaecology, Queen Mary Hospital, Hong Kong. Participants Eighty women presenting with prelabour rupture of membranes at term. Methods The women were randomised to receive either 100 mu g misoprostol or ally every 4 hours to a maximum of three doses, or intravenous oxytocin inf usion according to the hospital protocol. Intrauterine pressure transducers were inserted one hour before induction of labour in both groups of women. We compared the pattern of uterine activity, the induction-to-delivery int erval, duration of labour, mode of delivery and neonatal outcome between th e two groups. Results Both oxytocin and oral misoprostol caused an increase in uterine ac tivity within one hour of labour induction. Peak uterine activity was reach ed 6-8 h after oral misoprostol, with persistent: effects, and 8-10 h after oxytocin, requiring continuous titration of medication. The duration of la bour was significantly reduced in nulliparous women, but not in Chose who w ere multiparous in the misoprostol group. The induction-to-delivery interva l, the mode of delivery and the perinatal outcome were similar for the two groups. Conclusion Oral misoprostol caused earlier peak uterine activity, compared with oxytocin (6-8 h vs 8-10 h). Oral misoprostol was not only as effective as oxytocin in inducing labour in women at term with prelabour rupture of the membranes, but it reduced significantly the duration of labour in nulli parous women.