Misoprostol for induction of labour at term: a more effective agent than dinoprostone vaginal gel

To compare the efficacy of vaginal misoprostol and dinoprostone vaginal gel for induction of labour at term.

A single-blind randomised comparative trial.

Induction and labour wards of a UK teaching hospital.

Two hundred and eleven pregnant women at term in whom induction of labour was indicated, and with no contra-indication to the use of prostaglandins for the induction of labour.

The women were randomly assigned to receive vaginal administration of either misoprostol 50 microg four hourly (to a maximum of four doses) or dinoprostone gel 1 mg six hourly (to a maximum of three doses).

Time from induction to delivery, oxytocin requirement in labour, analgesic requirement, mode of delivery, neonatal outcome.

The misoprostol group had a highly significant reduction in median induction-delivery interval compared with the dinoprostone group (14.4 hours vs 22.9 hours; P < 0.00001). In addition, more women delivered after only one dose (77% vs 49%; P < 0.0001, OR 3.51, 95% CI 1.94-6.35), and within 12 and 24 hours. There was a reduced need for oxytocin augmentation in labour (21% vs 47%; P < 0.0001, OR 0.30, 95% CI 0.16-0.54). There was no difference in analgesia requirement in labour, or in mode of delivery. There were no adverse neonatal outcomes associated with the use of misoprostol. Women in the misoprostol group experienced more pain in the interval between induction and being given analgesia in labour, but this did not reach statistical significance.

Misoprostol 50 microg vaginally is a more effective induction agent than 1 mg dinoprostone vaginal gel, with no apparent adverse effects on mode of delivery, or on the fetus. The higher pain scores in the misoprostol group must be balanced against the reduction in time spent having labour induced, and the reduction in need for intravenous oxytocin augmentation. Further randomised studies must continue to exclude the possibility of rare adverse side effects.