Pain is a subjective experience. Different people have different pain thresholds; a stimulus experienced as pain by one may cause another only mild discomfort. Also an individual’s pain threshold can vary according to mood: for example, anxiety often sharpens the perception of pain.
In, the amount of pain felt depends not only on the mother’s pain threshold at the time but on the kind of she has. Although very few are fortunate enough to escape pain entirely, the knowledge that labour can be painful should not cause apprehension in a woman who is well prepared.
Knowing why pain happens, how long it is likely to last, and having attended antenatal classes to learn relaxation and, she will feel less anxious and more in control, even possibly coping with the discomfort without medical intervention. However, she will also know when she does need pain relief. Many women discover that, despite the best preparation, they still need some form of pain-killing medication ( ), which if chosen carefully and timed well should not spoil the joy of childbirth.
Pethidine is an effectivedrug often used in labour. It is given by intramuscular injection in doses of 50-200 mg, taking effect in about 15 minutes and lasting for two to four hours. For some, it has the added bonus of inducing a feeling of mild euphoria, but at the least it takes the edge off any anxiety. However, it does have some disadvantages. It can make the mother feel ‘drugged’ or ‘drunk’ and not in control. Others feel sick, and a minority actually vomit.
The most important adverse effect of pethidine is on the baby. Like many drugs, it passes across the placenta and, if given late in labour, may still be present in the baby’s blood when it is born. This can make the baby sleepy and it may need help, initially, to breathe. Fortunately, the effects wear off quite quickly. Sometimes an injection of another substance may be needed to counteract the drug, but there is no evidence that pethidine causes any permanent problems. The only other difficulties seem to be that the baby may take time to start feeding properly and the mother may take longer to get to know it, because the baby is not so alert. However, these can usually be overcome with encouragement from sympathetic nursing staff, especially if the mother is able to keep her baby by her for most of the time.
Another method of pain relief uses nitrous oxide, which, as a mixture with oxygen, is inhaled through a face mask. It goes under various trade names, such as Entonox, although it is often referred to simply as ‘ and ’. It is used widely in maternity hospitals, but it may not be available for home deliveries.
The amount of nitrous oxide can be varied, although normally in labour the mixture contains 50 per cent nitrous oxide and 50 per cent oxygen. Nitrous oxide (laughing) is an anaesthetic agent but, at this concentration, it does not cause loss of consciousness. As an analgesic, gas and air can be quite effective, yet some women find it helps them little, if at all. However, it is important to learn how to use it before going into labour. The antenatal teacher and hospital may arrange this. Timing is very important: gas and air starts to take effect after about half a minute but maximum pain relief occurs after another half-minute. A woman should, therefore, start breathing the gas as soon as the contraction begins and not wait until it is at its height. Gas and air is not as effective as pethidine, but it does have some advantages. The amount of nitrous oxide, and therefore the level of analgesia, can be controlled through the mask by breathing more or less deeply. Nitrous oxide also crosses the placenta, but does not build up in the baby’s body and is cleared with its first breaths. During the second stage of labour, when the effects of other analgesic drugs may have worn off, gas and air is particularly useful. It not only helps control the pain but also reduces the urge to bear down. Pushing before the cervix is fully dilated can damage the delicate tissue. At the end of the second stage it enables the baby to be delivered gently.
Epidural anaesthesia is becoming a popular way of controlling pain in labour, with some hospitals offering it routinely. At best it can make labour completely pain free. Increasingly, epidurals are being used for Caesarian sections, because a general anaesthetic carries a slight risk for both mother and baby. However, the main advantage is that a mother having a Caeserian section can see her baby born and hold it straight away.
The anaesthetic used for epidurals is similar to the local anaesthetic used by dentists. It is injected into the epidural space causing loss of sensation in the lower half of the body. This is a skilled job done by an anaesthetist.
An epidural takes time to set up and it is vital to stay absolutely still until the procedure is completed. If you think you may need an epidural you should ask for it well in advance, because it may be some time before the anaesthetist arrives, especially at night, and intense labour pains may make it difficult to keep still enough for the injection to be done easily.
After the skin has been numbed with a local anaesthetic and the first injection made, a fine, plastic tube, a catheter, is left in place taped to the skin of the back so that further anaesthetic can be given if necessary without another insertion.
However, late in the first stage of labour, giving an epidural, or topping up an existing one, may not be advisable. Because the anaesthetic almost eliminates the desire to push, the baby may need help –for example – to be born.
The epidural anaesthetic crosses the placenta, too, but in general these amounts are very small and most babies seem to suffer no ill effects.
Most hospitals now like to give an epidural if there is a complication such as breech presentation or high blood pressure because it makes the subsequent delivery of the baby easier and safer.
Other types of pain relief
Not all methods of pain relief involve drugs. Hypnosis or acupuncture may also help. Hypnosis can, for a small minority, completely banish pain. Others may benefit to some extent but may still need drugs as well. The attraction of hypnosis is that you can be taught to hypnotize yourself (auto-hypnosis) so that you do not need a qualified hypnotist to be present during labour.
If you choose acupuncture you must find a qualified acupuncturist prepared to stay with you all through labour. You must also check that the medical and nursing staff are happy with the arrangement. Many women find that giving birth by acupuncture is a rewarding experience, not only controlling pain but often making contractions more efficient.