Use of epidural analgesia and its relation to caesarean and instrumental deliveries-a population--based study of 94,217 primiparae.
To investigate the association between epidural analgesia for labour-pain relief and mode of delivery. The Swedish medical birth register covers 99% of all births and contains prospectively collected information from all delivery units in Sweden. The present population-based cohort study includes singleton births among nulliparae during 1998-2000, excluding deliveries with elective caesarean section, giving study population of n=94,217. The frequencies of epidural block in this population were estimated for each delivery unit. The outcomes studied were non-elective caesarean section and instrumental delivery. There was no clear association between frequency of epidural block and caesarean section and instrumental delivery, respectively. Delivery units with the lowest (20-29%) and the highest (60-64%) relative frequencies of epidural block had the lowest proportion of caesarean section (9.1%). For the other groups the proportion varied between 10.3 and 10.6%. Instrumental deliveries were most common, 18.8%, in delivery units with 50-59% frequency of epidural block use. The lowest incidence (14.1%) was in units using epidurals in 30-39% of cases. In the other groups (20-29, 40-49 and 60-64%) the proportion varied between 15.3 and 15.7%. This investigation shows no clear association between epidural use and caesarean section or instrumental delivery, indicating that there is no reason to restrict the epidural rate to improve obstetric outcome.