For most women, childbirth involves pain. The degree of pain and the person's response to it vary from one individual to another, and is related to one's emotional, motivational, social and cultural background. Hence, it is difficult for a woman or her doctor to anticipate her labour experience before the event itself. Ideally, a woman should discuss the various methods of relieving labour pain with her doctor during pregnancy, well before labour starts. Knowing the options available will enable the woman to make an informed decision when the time comes.

In normal labour, regular uterine contractions and progressive cervical dilatation eventually results in the delivery of the baby and the placenta. Uterine contractions, cervical dilatation, pressure on structures surrounding the uterus (fallopian tubes, ovaries, ligaments, rectum, bladder) and stretching of the perineum causes severe pain in most women. The perception of pain is increased if there is a lack of knowledge of the process of childbirth and / or a lack of support from caregivers or partners. What this means is that pain in labour and delivery has got physical and emotional components to it. Therefore, in trying to reduce that pain, the contributions of both should be addressed.

The preparation for coping with labour pain should start during pregnancy itself. Understanding the process of childbirth, its sources of pain and the alternatives available to relieve that pain may reduce some of the fear, anxiety and misconceptions that you might have. By so doing, the contribution of anxiety and fear of the unknown to labour pain may be reduced. It has been shown that attending childbirth education classes is associated with decreased pain in labour. Armed with knowledge of what is ahead and the options they have in dealing with labour pain may enable a woman to better cope with the event. Information may be obtained from traditional sources such as the obstetrician, books, family and friends or from the Internet. Performing aerobic exercises during pregnancy may be beneficial as some studies have shown that women who maintained a regular exercise programme enjoyed shorter and / or less painful labours.

In addition, it will help in building the stamina to cope with a physically demanding labour. Before embarking on an exercise programme, one should seek a doctor's advice and approval. The American College of Obstetricians and Gynaecologists has established guidelines to help prevent your core body temperature from rising too high and possibly harming your baby:

• Keep your heart rate under 140 beats per minute during exercise.
• Check your temperature by armpit at the end of your usual exercise to make sure it is less than 101 degrees (38.3 degrees Celcius).
• Limit very strenuous exercise to 15 minutes at a time.
• Replenish fluids after exercising.
• Avoid exercising outdoors in very hot weather or if you have a fever.

The ideal pain relief in labour should provide good a nalgesia, be safe for the mother and baby, be predictable and constant in its effects, be reversible if necessary, be easy to administer, and should not interfere with the labour process. Suffice to say, there is no ideal method yet at this point in time. There are both pharmacological (drugs) and non-pharmacological (no drugs) means of relieving labour pain. However, not all options are available in every hospital and it is important for you to discuss with your obstetrician what will be available to you in the hospital of your choice. The relative risks and benefits of various methods should be explained at that time so that you can make a plan that you are comfortable with. This does not mean that a decision made months before the actual labour is irreversible, since the character of your labour is an unknown factor.

Only when you are "tested" with the actual event will you know if the decision made earlier is the right one for you. Non-pharmacological means of relieving labour pain takes advantage of the fact that pain perception is malleable. You can try to send competing soothing messages to your brain by massage, therapeutic touch, local application of heat / cold or TENS (transcutaneous electrical nerve stimulation). You can employ positive imagery to interpret painful sensations. In Lamaze classes conducted during pregnancy, you would have been taught to breathe in a specific manner and to focus on an object or location during contractions. The increased concentration required to perform these "tasks" distract you from the painful contractions and prevent you from tensing up in anticipation of future pain. In addition, you can try changes of body position to reduce the pain caused by pressure on various structures surrounding the uterus. These techniques have varying degrees of success but most women will still require some form of pharmacologic pain relief.

Pharmacological means of relieving labour pain can be grouped into 3 types:

1. systemic medications
2. inhaled anaesthetics
3. regional techniques

I will discuss the commonly available ones of each. In this country, the commonest drug used to relieve labour pain is pethidine. An intramuscular (into muscle) dose of 50-100mg is given, with a peak effect 40-50 minutes later. The drug effect lasts about 3-4 hours. Pethidine will dull the pain of the contractions but in between the contractions, you may feel very sedated. It is prescribed by your obstetrician and does not require the additional services of an anaesthetist. The main disadvantage is that the drug will cross to the baby and may result in neonatal depression, especially if delivery occurs between 1-4 hours of the administration of the drug.

Another method is providing an inhaled anaesthetic agent, i.e. nitrous oxide in combination with oxygen. It is usually given at 50%, although higher concentrations may be available in some hospitals. The effect of 50% nitrous oxide is equivalent to 10mg morphine. Timing is crucial to the success of this technique; one should start breathing deeply on the nitrous oxide about 20-30 seconds before the next contraction and cease when the contraction is wearing off. The advantages of this technique are:

1. It is self-administered
2. Its rapid onset of action
3. Effects rapidly reverses when one stops inhaling the drug
4. It does not interfere with the labour process
5. There is no clinically adverse effects on the fetus
6. It is simple and inexpensive

Some of the side effects include nausea and vomiting, drowsiness and having hazy memories of labour. There is a low incidence of dizziness, dry mouth, numbness and/or tingling. It is rare for unconsciousness to occur with 50% nitrous oxide.

A fair proportion of women appear to obtain adequate pain relief and would use this technique again. It is more likely to be prescribed if the labour had progressed to a later part of the first stage or if the labour is expected to progress quickly as may be the case with women who have had previous deliveries.

The most effective method of providing pain relief in labour and delivery is by regional techniques, the commonest of which is the epidural. In the United States, it has been used for pain management during labour and delivery since the 1960s and as of 1997, nearly two-thirds of women who give birth in hospitals with high-volume obstetric units had an epidural during labour. In Malaysia, epidural for labour analgesia is still not widely used partly because there is a lack of qualified staff (it must be performed by an anaesthetist of which there is a shortage) and partly because there are misconceptions and misinformation on the part of the general public with regards to this method of pain relief.

'Epidural' refers to a technique whereby analgesia (pain relief) is achieved by injecting local anaesthetics (LA) with or without opioids into the epidural space surrounding the spinal column. This is accomplished by introducing a relatively large needle into the epidural space and pushing a fine catheter through the needle into the epidural space. The needle is then withdrawn, leaving the catheter in place. LA can then be administered through the catheter. During initial insertion of the needle and catheter, you will be assisted to curl your body forward, either lying on your side or sitting up. The area is cleansed with antiseptic solution and numbed with LA using a small needle before the large needle is introduced.

As with other techniques of providing pain relief in labour, there are risks with this one. The more common risks tend to be minor, while major risks are rare. Some of the more common risks or side effects include hypotension (a drop in blood pressure), shivering (unrelated to cold), inadequate pain relief and dural puncture (about 1), often resulting in a headache, which may be severe and require invasive form of treatment in some women. Major complications include nerve injuries, usually transient but may be permanent (0.02-0.07%) and even very rarely, cardiac arrest as a result of large volumes of local anaesthetic entering the blood circulation. However, even 'natural' childbirth has risks.

Apart from the risks, women should also be informed that with an epidural technique they may experience longer labours, that they are more likely to have an instrumental (forceps or vacuum) vaginal delivery and for reasons that are not yet determined, they have a higher incidence of fever. The implication of a higher rate of instrumental vaginal delivery is the increased rate of serious perineal lacerations that accompany its use. Should they develop a fever, their babies may be evaluated for infection, although there is no evidence that epidural increases infection in mothers or babies.

In these day and age, women no longer need to put up with pain in labour and delivery. There are many choices for pain relief in labour but in the end, the final decision should be made by the one who is feeling that pain. Information about the options for pain relief needs to be sought and obtained during pregnancy for it to be fully comprehended. Once labour pain has started, any information provided may not be 'heard'!

Some useful websites for information on labour and pain relief during labour are:
http://www.motherstuff.com/html/midwife-pain.html
http://sblomberg.com/epidural/
http://midwifeinfo.com/topic-epidurals.php

Contributed by:
Dr. Khoo En Szee
M.B.B.S. (U.M.), M.Med Anaes (U.M.)
FANZCA (Aust & N.Z.)
Consultant Anaesthetist, NMSC