19.2 Inducing labour at term

If labour does not start when you would like it to, you may be able to induce it. If it is going too slowly, you can speed it up. So distinguish between: (1) the induction of labour when the patient is not in labour, or only in the latent phase, and (2) the acceleration of labour, when she is in the active phase with her cervix >3 cm dilated. Here we are concerned with induction.

If the continuation of pregnancy would be harmful to a mother or to her baby, and especially if either of them is in danger of death, the logical solution might seem to be to induce labour and deliver them. Unfortunately, induction has its risks for both of them, so there are few indications for doing it in a district hospital. The commonest one is probably proven rupture of the membranes (23.4) lasting >12 hours, when she is near term (>37 weeks). All the other indications below are rare and relative.

Artificial rupture of the membranes (ARM), with an oxytocin IV or oral prostaglandins, is the most powerful way of inducing labour. Don’t do it for minor indications, because: (1) You may introduce infection when you rupture her membranes. If labour starts soon, the risk is small, but if it is delayed, the risk is large, especially if the baby is dead. Minimize this by taking the most careful aseptic precautions. (2) If you try to induce labour too soon: (a) the baby will be immature and have less chance of surviving, and (b) her labour is unlikely to start, and if it does start, it may so slow that you have to do a Caeseran section. So only induce labour, when the balance of risks favours it—when the surfactant test shows that he is mature, and Bishop’s inducibility test shows that her cervix is ripe, and ready for labour. (3) Inducing labour increases your Caesarean section rate, with all the disadvantages this has (22.1).

There are other risks: (4) Rupturing her membranes may cause the cord to prolapse. (5) Oxytocin may cause uterine rupture. (6) The placenta may separate. So never induce labour to suit your convenience or hers, but only for the soundest of obstetric reasons.

If her cervix is unfavourable, you can try ripening it with prostaglandins (expensive), or you can insert the balloon of a Foley catheter into her extra-amniotic space (cheap and effective).