Epidurals for pain relief in labour

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.

Authors' conclusions: 

Epidural analgesia appears to be effective in reducing pain during labour. However, women who use this form of pain relief are at increased risk of having an instrumental delivery. Epidural analgesia had no statistically significant impact on the risk of caesarean section, maternal satisfaction with pain relief and long-term backache and did not appear to have an immediate effect on neonatal status as determined by Apgar scores. Further research may be helpful to evaluate rare but potentially severe adverse effects of epidural analgesia on women in labour and long-term neonatal outcomes.

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Background: 

Epidural analgesia is a central nerve block technique achieved by injection of a local anaesthetic close to the nerves that transmit pain and is widely used as a form of pain relief in labour. However, there are concerns regarding unintended adverse effects on the mother and infant.

Objectives: 

To assess the effects of all modalities of epidural analgesia (including combined-spinal-epidural) on the mother and the baby, when compared with non-epidural or no pain relief during labour.

Search strategy: 

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 March 2011).

Selection criteria: 

Randomised controlled trials comparing all modalities of epidural with any form of pain relief not involving regional blockade, or no pain relief in labour.

Data collection and analysis: 

Two of the review authors independently assessed trials for eligibility, methodological quality and extracted all data. We entered data into RevMan and double checked it for accuracy. Primary analysis was by intention to treat; we conducted subgroup and sensitivity analyses where substantial heterogeneity was evident.

Main results: 

We included 38 studies involving 9658 women; all but five studies compared epidural analgesia with opiates. Epidural analgesia was found to offer better pain relief (mean difference (MD) -3.36, 95% confidence interval (CI) -5.41 to -1.31, three trials, 1166 women); a reduction in the need for additional pain relief (risk ratio (RR) 0.05, 95% CI 0.02 to 0.17, 15 trials, 6019 women); a reduced risk of acidosis (RR 0.80, 95% CI 0.68 to 0.94, seven trials, 3643 women); and a reduced risk of naloxone administration (RR 0.15, 95% CI 0.10 to 0.23, 10 trials, 2645 women). However, epidural analgesia was associated with an increased risk of assisted vaginal birth (RR 1.42, 95% CI 1.28 to 1.57, 23 trials, 7935 women), maternal hypotension (RR 18.23, 95% CI 5.09 to 65.35, eight trials, 2789 women), motor-blockade (RR 31.67, 95% CI 4.33 to 231.51, three trials, 322 women), maternal fever (RR 3.34, 95% CI 2.63 to 4.23, six trials, 2741 women), urinary retention (RR 17.05, 95% CI 4.82 to 60.39, three trials, 283 women), longer second stage of labour (MD 13.66 minutes, 95% CI 6.67 to 20.66, 13 trials, 4233 women), oxytocin administration (RR 1.19, 95% CI 1.03 to 1.39, 13 trials, 5815 women) and an increased risk of caesarean section for fetal distress (RR 1.43, 95% CI 1.03 to 1.97, 11 trials, 4816 women). There was no evidence of a significant difference in the risk of caesarean section overall (RR 1.10, 95% CI 0.97 to 1.25, 27 trials, 8417 women), long-term backache (RR 0.96, 95% CI 0.86 to 1.07, three trials, 1806 women), Apgar score less than seven at five minutes (RR 0.80, 95% CI 0.54 to 1.20, 18 trials, 6898 women), and maternal satisfaction with pain relief (RR 1.31, 95% CI 0.84 to 2.05, seven trials, 2929 women). We found substantial heterogeneity for the following outcomes: pain relief; maternal satisfaction; need for additional means of pain relief; length of second stage of labour; and oxytocin augmentation. This could not be explained by subgroup or sensitivity analyses, where data allowed analysis. No studies reported on rare but potentially serious adverse effects of epidural analgesia.