Randomized controlled comparison of epidural bupivacaine versus pethidine for analgesia in labour.

We compared the incidence of Caesarean delivery in nulliparous women randomized to receive epidural analgesia with those randomized to intramuscular (i.m.) pethidine. On admission to the delivery suite in established labour, 802 nulliparae had already agreed to be randomized with respect to their first analgesia. One hundred and eighty-eight women required either no analgesia or 50% nitrous oxide in oxygen (Entonox) only. Of the remaining 614 women, 310 were randomly allocated to receive i.m. pethidine up to 300 mg and 304 to receive epidural bupivacaine. Labour management was standardized according to the criteria for active management of labour. The intention-to-treat analysis showed similar Caesarean section rates in those randomized to epidural (12%) or pethidine analgesia (13%). The difference in Caesarean rate was -1.1% with 95% confidence intervals from -6.3% to +4.1%. The normal vaginal delivery rates were similar (epidural, 59%; pethidine, 61%).