A double blind controlled trial to study the effects of vaginal prostaglandin pessaries on induction of labour and improvement in the favourability of the cervix.

In a double blind trial of prostaglandin pessaries to induce labour, prostaglandins were successful in 47.5% of primiparous and 70.6% of multiparous patients. Of the 66% who did not go into labour this was successfully induced by artificial rupture of the membranes and oxytocin infusion in all but two cases irrespective of whether or not they received the active compound. This trial suggests that prostaglandin pessaries are a useful and very acceptable way of inducing labour and that although they make the cervix more "favourable" they do not significantly alter the outcome of labour. In the light of their high cost it is time that this method of induction and its timing was re-evaluated.