Induction of labour: the effect of vaginal prostaglandin or i.v. oxytocin--a matter of time only?

Ninety-one pregnant women with unfavourable cervix (Bishop score no higher than 6) were randomly allocated to induction of labour with either prostaglandin E2 suppositories 2.5 mg 1-2 a day or i.v. oxytocin 4-32 mU/min. The induction procedure was carried on for 2 days. For statistical comparison of efficacy, life table analysis and the logrank test were used with vaginal delivery as the aimed 'event'. Prostaglandin suppositories were more efficient after 12 h (p less than 0.025) and 24 h (p less than 0.005), whereas no difference in efficacy was observed after 48 h. Vaginal delivery was obtained within 48 h in 74% of the women in the prostaglandin group and in 70% in the oxytocin group. No difference was observed in methods of delivery or neonatal Apgar scores, though, in neonates delivered vaginally within 2 days, lowered umbilical artery blood pH values were found after prostaglandin E2 suppositories (p less than 0.05). The patients attitude toward the method of induction was highly in favour of the prostaglandin suppositories. Prostaglandin E2 suppositories are considered excellent for induction of labour if delivery has to be within 24 h, whereas the two methods are equally effective after 48 h.