Mothers-to-be often worry about labour pains that come with chidlbirth. The Department of Women’s Anaesthesia at KK Women's and Children's Hospital shares the options available for labour pain relief.
All mothers-to-be nearing childbirth worry about labour pain.
What causes labour pain?
In the first stage of labour, the pain is caused by the regular contraction and stretching of the womb and cervix that serve 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 as the woman pushes.
Labour pain increases in intensity and frequency as delivery approaches. Each woman will perceive labour pain differently, based on her previous experience, labour duration and the use of drugs to accelerate the progress of labour.
What are the options for labour pain relief?
Labour pain can be managed using several effective methods.
“Ideally, mothers should seek information regarding these options in the weeks or months before the due date, to allow time for informed decision-making,” says
Dr Eileen Lew, Head and Senior Consultant,
Department of Women’s Anaesthesia,
KK Women’s and Children’s Hospital (KKH), a member of the
Non-pharmacological methods (without drugs)
- Local heat or cold application
- Transcutaneous electrical nerve stimulation (also called ‘TENS’)
“These methods vary in their effectiveness but the majority of them have not been proven, by studies, to be effective,” says Dr Lew. “Some of these methods may be useful in short labour. Locally, these methods have not been widely used.”
Pharmacological methods (with drugs)
- Inhalation of a mix of gas and air (Entonox)
- Injection of opioids
- Epidural analgesia or combined spinal-epidural analgesia.
In this method, the mother inhales a gas mixture of 50 per cent nitrous oxide in oxygen, administered via a face mask or mouthpiece. This should be initiated as soon as the contractions begin so that maximal effect is achieved at the peak of the contractions. 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 per cent of labouring mums will find it satisfactory,” says Dr Lew. Entonox is readily available, does not stay in the body, and is easily administered. However, it can cause drowsiness, light-headedness and sometimes nausea.
The commonest opioid used for labour pain control is pethidine, usually injected into the thigh muscles. Pain relief is achieved in about 15 minutes and lasts up to three hours.
“However, an opioid injection cannot be given when the baby is about to be delivered (usually at least four hours before delivery). It is also limited to situations when the cervix is < 6cm dilated as it can cause drowsiness and breathing problems in the newborn,” says Dr Lew.
If these occur, an antidote known as naloxone has to be administered to the baby to reverse the side effects. In some obstetric units, the woman can self-administer opioid medication intravenously by pressing a button (a technique known as patient-controlled intravenous analgesia or PCIA). This is particularly useful when epidural analgesia cannot be administered for medical reasons.
“Whether injected into the muscles or the bloodstream, opioids can cause side effects such as drowsiness, nausea and vomiting. The woman may also have shallower and slower breathing,” says Dr Lew.
Epidural analgesia (EA) and combined spinal-epidural analgesia (CSEA)
Epidural analgesia (EA) is one of the most reliable and effective ways to relieve labour pain. Local anaesthetic drugs are injected in the epidural space, the outermost part of the spinal canal.
The combined spinal-epidural analgesia (CSEA) differs from EA in that an initial dose of the drug is injected into the spinal space, also within the spinal canal. This results in faster pain relief. The choice of EA or CSEA is usually left to the anaesthesiologist, as dictated by the stage and progress of labour.
Aside from pain relief, both EA and CSEA can help prevent the blood pressure from reaching critically high levels during labour, in women who suffer from pregnancy-induced hypertension.
Although EA/CSEA reduce labour pain to a great extent, some degree of pain may still be felt, especially when “pushing” the baby.
Patient-controlled epidural analgesia (PCEA)
Some tertiary obstetric hospitals like KKH offer patient-controlled epidural analgesia (PCEA), in which a pre-programmed device allows the mother to self-administer additional drugs into the epidural space. PCEA has advantages over conventional EA/CSEA in that the mother has better control over her pain and also consumes fewer drugs during labour.
“With so many options available, labour and childbirth should remain a meaningful and relatively pain free experience for all women,” says Dr Lew.
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