Early Compared With Late Neuraxial Analgesia in Nulliparous Labor Induction: A Randomized Controlled Trial

In observational studies, the rate of cesarean delivery among women who received epidural analgesia early in labor at cervical dilation less than 4 cm was twice that of women who first received epidural analgesia at greater cervical dilations. In contrast to these findings, 2 previous randomized studies, one a study of mixed spontaneous and induced labor and the other of spontaneous labor, as well as an extensive review of 9 studies reported no such association between timing of initiation of epidural analgesia and cesarean delivery rates. This randomized study investigated whether early initiation and maintenance of neuraxial (combined spinal-epidural) analgesia in nulliparas undergoing induction of labor increased the risk of cesarean delivery in comparison with systemic opioid analgesia in early labor followed by epidural analgesia in late labor. The final analysis included 806 singleton term nulliparas who were randomized to either combined spinal-epidural (early, n = 400) or systemic opioid (late, n = 406) analgesia at first request for analgesia when cervical dilation was ≤4 cm. Analgesia was maintained in the early group with patient-controlled epidural analgesia at the second analgesia request, whereas in the late group epidural analgesia was not initiated until the third request for analgesia. At the first and second analgesia requests, patients rated their pain using a verbal 0 to 10 rating score (0 indicating no pain). There was no difference in the cesarean delivery rate between the groups (early [combined spinal-epidural]: 32.7% vs. late [systemic]: 31.5%); the 95% confidence interval for the difference in the medians was -3% to 6% (P = 0.65). No differences between the groups were found in the mode of vaginal delivery or in Apgar scores at 1 and 5 minutes. The median pain scores were significantly lower in the early compared to the late group (early: 1 vs. late: 5, P < 0.001) and labor duration in the early group was shorter (early: median 528 minutes vs. late: 569 minutes, P = 0.047). After analgesia, there was no significant difference between the groups in the rate of reassuring fetal heart rate tracings, or in the incidence of persistent variable decelerations or late decelerations. These findings show no difference in the rate of cesarean delivery among a population of nulliparas undergoing induction of labor who received neuraxial analgesia in early as opposed to later labor.