Observations on labor epidural analgesia and operative delivery rates

Our purpose was to compare operative vaginal and abdominal delivery rates in a large population before and after on-demand labor epidural analgesia became available.

We retrospectively compared patients who gave birth during a 20-month period immediately before the introduction of an on-demand labor epidural analgesia service with those who gave birth during a 20-month period after the epidural usage rate had reached a plateau at approximately 60%. Operative vaginal and cesarean delivery rates were stratified according to parity and history of prior cesarean delivery.

A total of 4859 women gave birth during the study period when on-demand epidural analgesia was available, and 4778 women gave birth in the study period before the availability of on-demand epidural analgesia. Comparisons between the women with and those without on-demand availability of epidural analgesia demonstrated no statistically significant differences in the rate of spontaneous vaginal delivery (69.5% vs 68.3%), the overall cesarean delivery rate (19.0% vs 19.4%), the primary cesarean delivery rate (13.2% vs 13.4%), or the operative vaginal delivery rate (11.1% vs 11.9%) between the 2 periods. There were no statistically significant differences in mean gestational age at the time of delivery between the 2 groups, whereas there were statistically significant increases in the proportion of nulliparous women and in mean birth weight during the on-demand epidural period. Analysis after substratification of the study groups according to parity also revealed no statistically significant differences in the primary cesarean delivery rate or the proportion of women undergoing vaginal delivery. The sample size was adequate to exclude a 2% increase in the primary cesarean delivery rate between the 2 periods with 80% power. Subgroup analysis of the population of women who gave birth while epidural analgesia was available on request demonstrated that nulliparous parturient women who requested epidural analgesia were almost twice as likely to require operative vaginal or cesarean delivery as women who did not request epidural analgesia, a finding suggesting that women who request labor epidural analgesia have an inherent propensity toward operative delivery.

The introduction of an on-demand labor epidural analgesia service does not increase the rate of cesarean delivery or operative vaginal delivery.