Prostaglandins as therapy for labour induction or therapeutic abortion

(a) Prostaglandins (especially PGE2) are highly effective for ripening the cervix and inducing labour. If the cervix is already ripe, a small dose of PGE2 may be all that is required to initiate a labour which resembles spontaneous labour as closely as possible. (b) Amniotomy is the central event. Although it is possible for an infant to be born in the caul, i.e. in intact membranes, it is the general rule for the membranes to rupture or to be ruptured during labour. Such rupture leads to heightened activity of endogenous prostaglandins. The timing of amniotomy is crucial. Performed too early, before the cervix is ripe, it may lead to complications. Delayed too late, we may lose the advantage of its uterine sensitizing. (c) Oxytocin is a potent myometrial stimulant if the uterus is primed to respond to it by prostaglandins, either endogenous or exogenous. It must be given intravenously and many mothers find this disagreeable. In most instances of labour induction, a proper combination of prostaglandin therapy and amniotomy may allow the use of oxytocin to be avoided, but it remains the therapy of final resort to carry labour through to delivery if required.