The intensity of labour pain is greater than that for most acute and chronic pain syndromes. ~ As such, it is a powerful stimulus and may produce undesirable effects in the mother and fetus. 2 These include increases in maternal blood pressure, cardiac output and catecholamine release. Maternal hypervenlilation during contractions followed by periods of hypoventilation during uterine relaxation may cause a decreased maternal PaO2 during the relax- ation phase with a corresponding decrease in fetal oxygenation. Hyperventilation also causes a maternal respiratory alkalosis which has the potential to decrease umbilical blood flow and oxygen transfer to the fetus. Effective analgesia, through elimination of the pain component, may: (I) interrupt the hypo-hyperventilation cycle with normalization of maternal PaCO2 and PaO2, (2) decrease catecholamine release, (3) offset that portion of increased cardiac output secondary to pain, and (4) improve circulation and oxygenation to the fetus. Epidural analgesia provides excellent pain relief for the parturient with minimal side-effects and has achieved popularity in obstetric units throughout the country. However, provision of epidural analgesia is not always feasible nor is it applicable to all situations. Many small communities have active obstetric units but limited availability of anaesthetic personnel. 3 With a relatively small obstetric case load it may not be possible to maintain the necessary skills to provide safe, effective epidural anaesthesia. 4 As well, epidural anaesthesia is contra- indicated in situations of patient refusal, presence of coagulopathy or infection, and haemodynamic instabili- ty. Under these circumstances, other analgesic modalities must be used, either alone or in combination. Psychopro- phylaxis (Lamaze) and TENS (Transcutaneous Electrical Division of Obstetric Anaesthesia,the University of British Columbia and Grace Hospital, Vancouver, British Columbia. Nerve Stimulation) are non-pharmacological options, while inhalational analgesia with nitrous oxide/oxygen mixtures, and systemic or spinal narcotics provide more potent pain relief. Psychoprophylaxis (Lamaze) is a drug-free technique based on decreasing or eliminating pain and anxiety during labour. To be effective the parturient must be highly motivated. In late pregnancy, the parturient and her partner participate in lectures on the anatomy and physiology of labour and delivery, the causes of pain, and exercises to promote relaxation and distraction. Advan- tages include lower pain scores ~ and more informed and cooperative patients. Fatigue may counteract the benefi- cial effects during long, difficult labours. Described as a form ofelectrical acupuncture, TENS has the advantage of simplicity and of being non- depressant to the fetus and mother. For the first stage of labour, electrodes are placed over the T~o-L~ dermatomes on either side of the spine and low intensity stimulation is used continuously. A higher level is switched on during contractions. A blinded study involving TENS and TENS placebo did not demonstrate any difference in pain relief but patient satisfaction and acceptance was high. s Previ- ous training is said to increase its effectiveness. The major disadvantage is interference with electronic fetal monitoring. Intermittent inhalation of a 50% mixture of nitrous oxide and oxygen provides effective analgesia in approxi- mately 40% of parturients. 6 The advantages of rapid pulmonary uptake and excretion, self-administration and a proven safety record make it a particularly useful technique. For maximum benefit, the parturient applies the mask tightly to her face and, beginning with the onset, breathes rapidly and deeply throughout the contraction. Symptoms of hyperventilation and drowsiness may occur with prolonged use. Narcotics have been used effectively for labour pain for many years. Systemic administration of these agents has fallen into disfavour because of the frequency of maternal side-effects (nausea, vomiting, dysphoria, drowsiness) and the potential for neonatal respiratory depression and prolonged neurobehavioural changes. Small doses of intrathecal morphine (0.2-1.0 mg) have