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

Presented in abstract form at the Annual Meeting of the Society for Obstetric Anesthesia and Perinatology, April 1997.
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Abstract

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. (Am J Obstet Gynecol 1998;179:1527-33.)

Section snippets

Methods

Approval for the study protocol was granted by the Human Studies Review Committee of the University of Louisville. Spontaneously laboring nulliparous patients admitted to the labor and delivery unit at the University of Louisville Hospital were invited to participate in the study. A patient was considered eligible for enrollment if the following criteria were met: (1) patient was nulliparous, (2) gestational age was ≥36 weeks, (3) presentation was vertex, and (4) patient was in spontaneous

Results

From January 1, 1995, to May 25, 1996, a total of 328 patients gave consent to enroll in the study. Ten patients were excluded from the data analysis because of protocol violations, including patients admitted for labor induction, multiparous patients, and an estimated gestational age <36 weeks. Of the 318 remaining patients, 162 were randomly assigned to receive intravenous opioids and 156 were randomly assigned to receive epidural analgesia. As shown in Table I, the randomization resulted in

Comment

This study is the fifth randomized trial conducted in the United States to evaluate the effect of epidural analgesia on cesarean delivery rates. In contrast to the first 2 studies,6, 7 we found no increase in cesarean delivery rates, either overall or for dystocia, associated with the use of epidural analgesia. The first randomized trial comparing epidural analgesia with intravenous opioids was reported in 1993 by Thorp et al.6 In this trial of 93 nulliparous, spontaneously laboring women, the

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  • Cited by (0)

    Reprint requests: Ann L. Clark, MD, Department of Obstetrics and Gynecology, University of Louisville School of Medicine, Louisville, KY 40292.

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