The influence of epidural analgesia on cesarean delivery rates: A randomized, prospective clinical trial

OBJECTIVE: The effects of epidural analgesia on the progress of labor are c ontroversial. The objective of this study was to determine the effect of ep idural analgesia on cesarean delivery rates in a population of patients ran domly assigned to receive either epidural analgesia or intravenous opioids for intrapartum pain relief. STUDY DESIGN: From January 1995 to May 1996, 318 spontaneously laboring, te rm, nulliparous patients were randomly assigned to receive either intraveno us opioids or epidural analgesia for pain relief. Labor was managed accordi ng to the principles of active management of labor. Cesarean delivery was p erformed for obstetric indications. Data analysis was conducted on an inten t-to-treat basis. A subanalysis was subsequently performed on patients who were compliant with the allocated form of treatment. RESULTS: One hundred sixty-two patients were randomly assigned to receive i ntravenous meperidine and 156 were randomly assigned to receive epidural an algesia. Maternal age, gravidity race, gestational age, and cervical dilata tion at admission and at first analgesic dose did not differ between the gr oups. Intent-to-treat data analysis revealed ilo significant difference in the cesarean delivery rate between the 2 groups, being 13.6% in the opioid group and 9.6% in the epidural group (relative risk 0.70, 95% confidence in terval 0.38-1.31, P >.05). Cesarean delivery rates for the indication of dy stocia also did not differ, being 10.5% in the opioid group and 5.8% in the epidural group (relative risk 0.56, 95% confidence interval 0.26-1.21, P > .05). Subanalysis of the data from patients who were compliant with the all ocated form of treatment revealed that patients in the epidural group (n = 147) were 3 times more likely to have an active phase duration greater than or equal to 8 hours and were 10 times more likely to require greater than or equal to 2 hours in the second stage of labor than were those in the opi oid group (n = 78). There were no significant differences in cesarean deliv ery rates in this subanalysis, being 7.7% in the opioid group and 8.8% in t he epidural group (relative risk 1.15, 95% confidence interval 0.45-2.91, P >.05). The cesarean delivery rates for dystocia were also similar in the su banalysis, being 3.8% in the opioid group and 5.5% in the epidural group (r elative risk 1.42, 95% confidence interval 0.39-5.22, P >.05). CONCLUSION: Epidural analgesia provides safe and effective intrapartum pain control and may be administered without undesirable effects on labor outco me.