Induction of labour is an obstetric procedure that is designed to pre-empt the natural process of labour by initiating its onset artificially before it occurs spontaneously. The decision to induce labour is usually taken to serve some interest, most usually that of the baby, less often that of the mother and sometimes that of the obstetrician and medical service. Few issues have generated as much controversy as this one, particularly in the days when the ability to induce labour seemed to outstrip sound clinical judgment.
It is rare these days for labour induction to have to be considered with regard to the mother’s health. In years past, if women had a chronic medical condition, such as heart or kidney disease, they were advised not to have children and, if they got pregnant, to have a termination. The worry was always that the additional stress of pregnancy might cause a dangerous deterioration in their condition. The new methods of inducing labour allow obstetricians to interrupt a pregnancy if and when it threatens the mother’s life, and not before-and hopefully at a stage when the baby is sufficiently advanced to have a good chance of healthy survival.
Intervention can only ever be appropriate when its risks are judged to be fewer than those which might result if no intervention is made. There are certainly pregnancy complications which carry clearcut risks for the baby- rhesus disease, diabetes and severe pre-eclampsia being the most obvious examples. Yet even in these situations the decision when to deliver the baby may be becoming more and more anaemia, but from complications associated with prematurity.
One fairly common reason for induction is that the bay is overdue, but the evidence for induction here is even less clearcut. Some obstetricians are relaxed about babies being overdue, regarding it as a variation of normal and following a policy of `expectant management’. Others are much keener to end pregnancy at `term’ i.e. at 40 weeks, especially for pregnancies in older women and there is no doubt that some doctors employ emotional blackmail, suggesting that a woman’s failure to agree to inductions will put her baby at risk. Women themselves are evenly divided about induction; at 42 weeks, an equal proportion will accept and refuse induction. Only 4 per cent of babies are born on the due delivery date. Whilst some women are happy to wait, others find the days after that magic date are quite interminable. Your friends won’t help either, saying things like, `are you still here?’
Being past your delivery date doesn’t win prizes for comfort for sure, but what is the evidence for it being harmful to the baby? The justification for induction is that I the past there was a clear increase in baby deaths associated with being born past term. However, these figures were skewed by the inclusion of babies with particular types of lethal handicap, most notably anencephaly, which are associated with prolonged pregnancy. These conditions were not detected antenatally as they would be today. There is no scientific justification for a policy of delivering all babies electively after 280 days (40 weeks ) in order to prevent post-term pregnancy altogether. But the evidence thereafter, one way or another, is either lacking altogether or very scanty. If you are happy to sit it out, however, you might feel more reassured if you had monitoring every couple of days or so.
There are one or two myths about induction that are worth scotching. One is that women are more likely to have caesarean; this simply isn’t borne out by the figures. Also, it is always said that induced labour is likely to be more painful and that there is therefore a higher rate of epidural use. Whilst the former statement may have some truth, the latter does not, which is surprising given that epidurals are more likely to be available during working hours, when inductions are most likely to be carried out.
Over the years, many women have given me their suggestions as to how to get labour started naturally. The only element here with any science behind it is having sex. Semen contains prostaglandins (hormone-like substances). Prostaglandins, it appears, are the pump primers as far as getting the womb into contraction mode is concerned. They also play a central role in the `ripening’ of the cervix. Incidentally, oxytocin is also released naturally when you twiddle your nipples in late pregnancy (as you do) and someone undertook a trial showing that women who spent an average of three hours a day either twiddling their nipples or (and this is the bit I prefer ) having them twiddled for them, went into labour significantly earlier than women who didn’t nipple-twiddle. I suppose it occupies the day.
You may hear all sorts of other things suggested such as taking purgatives like castor oil. The thought here is that the unpleasant attack of diarrhea that may follow might precipitate labour. On the other hand, you might still have an unshiftable bulge and be constantly running up and downstairs to the loo. In all seriousness, I wouldn’t recommend this sort of approach; nasty diarrhea can leave you feeling weak and debilitated and that’s the last way you want to feel when you go into labour.
If you think about it, your womb and cervix have to reverse their roles completely during labour. The womb has to go from being a muscular holding bag that does not contract, to being a bag that contracts so much that the contents are expelled. And the cervix has to go from being a rigid plug, to being soft and pliant. Although this process may seem to be a sudden one, in reality it is the culmination of a gradual process evolving over a period of weeks. During this period of pre-labour, the womb practices contractions and the cervix `ripens’. This curious obstetric expression means that the cervix softens itself so that, when the moment arrives, it will be able to dilate rapidly.
There are only three board approaches to induction of labour
- sweeping of the membranes (also called stripping),
- amniotomy (breaking the membrances)
- and the use of drugs such as prostaglandins or oxytocin
You could pump in oxytocin (the hormone use to speed up labour) by the truckload early in pregnancy and it would have no effect. But the womb can be made responsive oxytocin if prostaglandins (which are hormone-like substances) are administered first. In some ways all labour induction is really labour acceleration because all it is doing is bringing forward an inevitable prospect. The method of induction that is used is dependent on where you are on the continuum-pregnancy, pre-labour, (i.e. when you’ve started and then stopped again), active labour, delivery-and the closer you areto labour proper, the easier it is going to be to induce labour.
`Sweeping’
involves inserting a finger through the cervix and sweeping it around between the membranes and the womb. Some people say it can be painful. It can be quite excruciating. Often sweeping is to set you off in labour and it’s usually done in the hope that pessaries and the like can be avoided in the very late stages of pregnancy.
If you are still some weeks away from your delivery date and need to be induced, or even if you are at term but just have a baby that won’t budge, techniques such as this are no good. Even if you went into labour, the celvix wouldn’t beready to dilate. Thus, before the pharmaceutical big guns can be brought in, the cervix need to be `ripened’ by using prostaglandins. These substances are not circulating hormones like oestrogen, but are produced very close to the organ that they act upon. Because of the speed with which circulating prostaglandins are rendered inactive, doses given by mouth have of necessity, to be very large and may provoke troublesome side effects. One way to overcome this, however, is to give smaller doses of prostaglandin very frequently-say one tablet every hour. But most prostaglandins are administered as vaginal pessaries or gels. The most familiar brand names you will hear Prostin, Cervagem or Prepidil (a gel).
Amniotomy
Once your cervix has begun to dilate, your membranes may be broken. This is called by various names-artificial rupture of the membranes (ARM) or amniotomy, in which a special hook is used. It is quite likely that this is all you will need to put you into strong labour. There is usually a noticeable change of gear once the waters have broken, partly because the baby is now pressing directly on the cervix instead of having a cushion of fluid to press on, and labour may become a lot more intense and painful for some women at this stage. Actually even if women are in established early labour, their waters will probably be broken. There are no sense endings in the amniotic sac and therefore amniotomy isb painless.
Oxytocin
The final weapon in the induction armoury is the hormone oxytocin. In the same way that amniotomy wouldn’t be any good prior to use of prostaglandins, oxytocin won’t work before the membranes are break, the womb suddenly becomes receptive to oxytocin. Oxytocin is more likely to be used when when your waters have gone, but you haven’t yet gone into labour. It is also used extensively to augment labour if it has slowed down. It is usually administered as an intravenous infusion controlled by a mechanical infusion pump. Synthetic oxytocin is dispensed under its brand name, Synthetic oxytocin is dispensed under its brand name, Syntocinon. The dosage is started at a fairly low rate and then built up gradually. When oxytocin is used, the baby will be monitored continuously using a fetal scalp electrode, because the strength of the artificial contractions may affect it.
There is no doubt that an oxytocin-speeded labour is likely to be more intense and 80 per cent of women will find it more painful. It will also be attached to the drip, you will not be able to move around in the same way as if you were unattached to the drip, you will not be able to move around in the same way as if you were unattached. If you are having an oxytocin drip to speed up a slow labour, you might like to try some other methods first- like walking around, or having something to drink and eat ( providing it is light), as this may do the trick. You might think that an oxytocin-augmented labour is shorter, but one study has shown that a control group in which women were mobile in labour is shorter, but one study has shown that a control group in which women were mobile in labour had shorter labour times than the drug-augmented group. It is also the case that about half of women judged to have slow labours or poor progress in cervical dilatation will progress equally well whether or not oxytocicdrugs are given. But remember, half of them needed the oxytocic drugs.
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