Early versus late epidural analgesia and risk of instrumental delivery in nulliparous women: a systematic review.

Objective: Review of the literature regarding the relation between the timing of epidural analgesia and the rate of caesarean or instrumental vaginal deliveries.
Search Strategy: Pubmed, Embase and the Cochrane Library were searched for articles published until 31 July 2010.
Selection Criteria: Studies were selected in which the effects of early latent phase (defined as a cervical dilatation of 3 cm or less) epidural analgesia (including combined-spinal epidural) and late active phase epidural analgesia on the mode of delivery in nulliparous women at 36 weeks of gestation or more were evaluated.
Data Collection and Analysis: Data extraction was completed by using a data-extraction form. Risk ratio and its 95% confidence intervals were calculated for caesarean delivery and instrumental vaginal delivery. Pooled data were calculated.
Main Results: The search retrieved 20 relevant articles, of which six fulfilled the selection criteria of inclusion. These six studies reported on 15,399 nulliparous women in spontaneous or induced labour with a request for analgesia. Risk of caesarean delivery (pooled risk ratio 1.02, 95% CI 0.96-1.08) or instrumental vaginal delivery (pooled risk ratio 0.96, 95% CI 0.89-1.05) was not significantly different between groups.
Authors' Conclusions: This systematic review showed no increased risk of caesarean delivery or instrumental vaginal delivery for women receiving early epidural analgesia at cervical dilatation of 3 m or less in comparison with late epidural analgesia.
(© 2011 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2011 RCOG.)