Objective: To compare the effects of epidural analgesia with intravenous (IV) analgesia on the outcome of labor.
Methods: Thirteen hundred thirty women with uncomplicated term pregnancies and in spontaneous labor were randomized to be offered epidural bupivacaine-fentanyl or IV meperidine analgesia during labor.
Results: Comparison of the allocation groups by intent to treat revealed a significant association between epidural allocation and operative delivery for dystocia. However, only 65% of each randomization group accepted the allocated treatment. Four hundred thirty-seven women accepted and received meperidine as allocated, and they were compared with 432 women accepting epidural allocation. Significant associations resulted between epidural administration and prolongation of labor, increased rate of oxytocin administration, chorioamnionitis, low forceps, and cesarean delivery. Because of the high rate of noncompliance with treatment allocation, a multifactorial regression analysis was performed on the entire cohort, and a twofold relative risk of cesarean delivery persisted in association with epidural treatment. The impact of epidural treatment on cesarean delivery was significant for both nulliparous and parous women (risk ratios 2.55 and 3.81, respectively). Epidural analgesia provided significantly better pain relief in labor than did parenteral meperidine.
Conclusion: Although labor epidural analgesia is superior to meperidine for pain relief, labor is prolonged, uterine infection is increased, and the number of operative deliveries are increased. A two- to fourfold increased risk of cesarean delivery is associated with epidural treatment in both nulliparous and parous women.