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As the due date for the birth of the baby approaches, one of the biggest worries facing all mothers is the pain from the labour process​. After all, it has been reported that most women experience significant pain during labour and childbirth. 

What is Labour Pain? 

With the onset of the first stage of labour, the pain is caused by regular contraction and stretching of the womb and cervix that serves to open the cervix. This stage may last from 8 to 12 hours for first-time mothers. The second stage of labour begins when the baby descends through the birth canal, aided by the mother’s pushing. Labour pain is not constant, but increases in intensity and frequency with the progress of labour. 

Different women perceive labour pain differently. This perception may be influenced by the woman’s previous labour experience, duration of the labour and the use of drugs to accelerate the progress of labour. 

What are My Options for Labour Pain Relief? 

Childbirth is not a test of endurance. In the age of modern medicine, there are now effective methods for the management of labour pain. Ideally, mothers should seek information regarding these options in the weeks or months before the due date, to allow time for informed decision-making. 

Non-pharmacological methods (i.e. not using drugs)

Examples include: hypnosis, hydrotherapy, local heat or cold application, transcutaneous electrical nerve stimulation (also called ‘TENS’), acupuncture techniques. These methods vary in their effectiveness but the majority of them have not been proven by studies to be effective. Some of these methods may be useful in short labours. Locally, these methods have not been widely used. 

Pharmacological Methods (i.e. using drugs) 

Examples include: inhalation of entonox gas, injection of opioids, epidural or combined spinal-epidural analgesia. ​

Entonox Inhalation 

In this method, the mother inhales a gas mixture of 50% nitrous oxide in oxygen, administered via a tight-fitting facemask or mouthpiece. For effective use, the mother should start breathing the gas as soon as contraction begins, so that maximal effect is achieved at the peak of contraction. Entonox inhalation does not eliminate pain but merely alters the mental state so that the pain is felt less acutely. 

The effectiveness of entonox in the relief of labour pains varies from individual to individual. In general, up to 50% of labouring mums will find this a satisfactory form of pain relief. 

Advantages: readily available, does not stay in the body system, and easily administered. 

Disadvantages: causes drowsiness, light-headedness and nausea. 

Opioid Injections 

The commonest opioid used for labour pain control is pethidine. The midwife upon request usually injects it into the muscles of the thigh. Each injection takes about 15 minutes for onset of effect and provides two to three hours of pain relief. However, it cannot be given when the baby is about to be delivered (usually at least 4 hours before delivery and is limited to situations when the cervix is < 6 cm dilated), as it can cause drowsiness and breathing problems in the newborn. If these occur, an antidote known as naloxone has to be administered to the baby to reverse the side effects. 

In KK Hospital, devices are available that allow the mother to self-administer short-acting opioid medication into the blood stream intravenously by pressing a button (a technique known as ‘Patient-Controlled Intravenous Analgesia’ or PCIA). This is particularly useful as an alternative for pain relief in situations when epidural analgesia cannot be administered, such as in mothers with bleeding tendencies such as low platelet levels or spinal problems such as prolapsed intervertebral discs. 

Whether injected into the muscles or the blood stream, known side-effects of opioids to the mother include drowsiness, nausea and vomiting. The mother may also have shallower and slower breathing. 

Epidural Analgesia (EA) 

Epidural analgesia (EA) is one of the most reliable and effective ways to relieve labour pain. Pain relief is achieved by the injection of local anesthetic drugs through a small tube into the epidural space within the backbone canal performed by a trained anesthetist. 

The Combined Spinal-Epidural Analgesia (CSEA) differs from EA in that an initial dose of drug is given into the spinal space, which is also within the backbone canal. This results in a faster onset of pain relief. The decision for EA or CSEA is usually left to the discretion of the anesthetist, as dictated by the stage and progress of labour.​ 

Different positions for administering epidural

Although EA/CSEA reduces labour pain to a great extent, some degree of pain may still be felt, especially at the time of “pushing” of the baby. 

Other benefits of EA/CSEA​

EA/CSEA can also help in the control of blood pressure of mothers with high blood pressure in pregnancy — a condition called “pregnancy-induced hypertension”. As such, it can prevent the blood pressure from reaching critically high levels during labour.

Patient-controlled Epidural Analgesia (PCEA) 

KK Hospital now offers a technique known as Patient-Controlled Epidural Analgesia’ or PCEA, wherein a pre-programmed device allows the mother to administer additional drugs into​ the epidural space by the push of a button. PCEA has greater advantage over conventional EA/CSEA in that the mother has better control over her pain and also uses less drugs during labour. 

Myths Associated with An Epidural Analgesia 

1. There are many side effects associated with an epidural usage. 

Some minor side effects may occur but they are often minor, transient and self-limiting. These include: 

  • ​​Loss of feeling and muscle weakness - Numbness of the legs and lower part of the body is to be expected. The urge to pass urine may also be lost momentarily, but this can be rectified by intermittent drainage of the urine by the midwife. As the epidural drug effect wears out, sensation and strength of the legs and lower body are restored. 
  • Nausea - This may result from a lowering of the mother’s blood pressure or direct effect of the epidural drugs used. It may be treated with proper positioning and pressure-boosting medicines. 
  • Shivering - This may occur although the woman may not actually feel cold. Harmless to mother and baby, it usually does not require any treatment. 
  • Itch - Mild itch on the body is more common after CSEA than EA. Usually self-limiting, it does not need any treatment. 
  • Spinal headache - There is a risk of a spinal headache of about 1% after EA/CSEA. The headache usually occurs after delivery and is worsened by the upright posture. Medications and a procedure called epidural “blood patch” can be used to treat the headache, if severe. In most cases, the headache resolves with time. 

2. An epidural causes long term backache. ​

Conducted studies have failed to establish a link between long-term backache and EA/CSEA. Backache is common after childbirth, with or without the use of EA/CSEA. Proper back care during pregnancy and after childbirth is important.​

3. An epidural harms the baby. 

EA/CSEA does not harm the baby. However, some temporary changes in the baby’s heartbeat may occur. 

4. An epidural can cause paralysis. 

This is actually very rare. The risk of a permanent damage is actually 1 in 50000–100000. The risk of paralysis is one in a million. 

5. An epidural can be life threatening. 

These are actually very rare and include high blocks, breathing difficulty, convulsions, nerve damage and spinal infection. High standards of medical practice and proper patient selection have contributed to the safety of these procedures. 

6. An epidural prolongs the labour and increases the risk of a cesarean section. 

EA/CSEA does not result in a greater risk of cesarean section for the mother. There may be a slightly increased risk of instrumental delivery​ with an epidural. The benefits of EA/CSEA do outweigh the possible side effects associated with it. 

Acknowledgement

Source: Dr TAN Thiam Chye, Dr TAN Kim Teng, Dr TAN Heng Hao, Dr TEE Chee Seng John, The New Art and Science of Pregnancy and Childbirth, World Scientific 2008.