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Rates of caesarean section and instrumental vaginal delivery in nulliparous women after low concentration epidural infusions or opioid analgesia: systematic review

BMJ 2004; 328 doi: (Published 10 June 2004) Cite this as: BMJ 2004;328:1410
  1. E H C Liu, consultant (analiue{at},
  2. A T H Sia, consultant2
  1. 1 Department of Anaesthesia, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074
  2. 2 Department of Obstetric Anaesthesia, KK Women's and Children's Hospital, Singapore
  1. Correspondence to: E H C Liu
  • Accepted 18 March 2004


Objective To compare the effects of low concentration epidural infusions of bupivacaine with parenteral opioid analgesia on rates of caesarean section and instrumental vaginal delivery in nulliparous women.

Data sources Medline, Embase, the Cochrane controlled trials register, and handsearching of the International Journal of Obstetric Anesthesia.

Study selection Randomised controlled trials comparing low concentration epidural infusions with parenteral opioids.

Data synthesis Seven trials fulfilled the inclusion criteria for meta-analysis. Epidural analgesia does not seem to be associated with an increased risk of caesarean section (odds ratio 1.03, 95% confidence interval 0.71 to 1.48) but may be associated with an increased risk of instrumental vaginal delivery (2.11, 0.95 to 4.65). Epidural analgesia was associated with a longer second stage of labour (weighted mean difference 15.2 minutes, 2.1 to 28.2 minutes). More women randomised to receive epidural analgesia had adequate pain relief, with fewer changing to parenteral opioids than vice versa (odds ratio 0.1, 0.05 to 0.22).

Conclusions Epidural analgesia using low concentration infusions of bupivacaine is unlikely to increase the risk of caesarean section but may increase the risk of instrumental vaginal delivery. Although women receiving epidural analgesia had a longer second stage of labour, they had better pain relief.


  • Contributors EL conceptualised the review. EL and AS independently searched for, collated, assessed, and analysed the data, and cowrote the paper. EL will act as guarantor for the paper

  • Funding None.

  • Competing interests None declared.

  • Ethical approval Not required.

  • Accepted 18 March 2004
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