Pain relief is important for women in labour. Pharmacological methods of pain relief include inhalation of nitrous oxide, injection of opioids and regional analgesia with an epidural for a central nerve block. Epidurals are widely used for pain relief in labour and involve an injection of a local anaesthetic into the lower region of the spine close to the nerves that transmit pain. Epidural solutions are given by bolus injection, continuous infusion or using a patient-controlled pump. Lower concentrations of local anaesthetic are needed when they are given together with an opiate, allowing women to maintain the ability to move around during labour and to bear down. Epidural analgesia may sometimes give inadequate analgesia, which may be due to non-uniform spread of local anaesthetic. Combined spinal-epidural involves a single injection of local anaesthetic or opiate into the cerebral spinal fluid for fast onset of pain relief as well as insertion of the epidural catheter for continuing pain relief. Side effects such as itchiness, drowsiness, shivering and fever have been reported and rare but potentially severe adverse effects of epidural analgesia do occur.
The review identified 38 randomised controlled studies involving 9658 women. All but five studies compared epidural analgesia with opiates. Epidurals relieved labour pain better than other types of pain medication but led to more use of instruments to assist with the birth. Caesarean delivery rates did not differ overall and nor were there effects of the epidural on the baby soon after birth; fewer babies needed a drug (naloxone) to counter opiate use by the mother for pain relief. The risk of caesarean section for fetal distress was increased. Women who used epidurals were more likely to have a longer delivery (second stage of labour), needed their labour contractions stimulated with oxytocin, experienced very low blood pressure, were unable to move for a period of time after the birth (motor blockage), had problems passing urine (fluid retention) and suffered fever. Long-term backache was no different. Further research on reducing the adverse outcomes with epidurals would be helpful.