Objective: The effects of epidural analgesia on the progress of labor are controversial. The objective of this study was to determine the effect of epidural analgesia on cesarean delivery rates in a population of patients randomly assigned to receive either epidural analgesia or intravenous opioids for intrapartum pain relief.
Study design: From January 1995 to May 1996, 318 spontaneously laboring, term, nulliparous patients were randomly assigned to receive either intravenous opioids or epidural analgesia for pain relief. Labor was managed according to the principles of active management of labor. Cesarean delivery was performed for obstetric indications. Data analysis was conducted on an intent-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 intravenous meperidine and 156 were randomly assigned to receive epidural analgesia. Maternal age, gravidity, race, gestational age, and cervical dilatation at admission and at first analgesic dose did not differ between the groups. Intent-to-treat data analysis revealed no 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 interval 0.38-1.31, P >.05). Cesarean delivery rates for the indication of dystocia 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 allocated form of treatment revealed that patients in the epidural group (n = 147) were 3 times more likely to have an active phase duration >/=8 hours and were 10 times more likely to require >/=2 hours in the second stage of labor than were those in the opioid group (n = 78). There were no significant differences in cesarean delivery rates in this subanalysis, being 7.7% in the opioid group and 8.8% in the 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 subanalysis, being 3.8% in the opioid group and 5.5% in the epidural group (relative 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 outcome.