Effect of epidural vs parenteral opioid analgesia on the progress of labor: a meta-analysis.

CONTEXT Epidural labor analgesia, if selected by the patient, is associated with high cesarean delivery rates. Results of randomized trials comparing rates of cesarean delivery using epidural anesthesia vs parenteral opioids are inconsistent. OBJECTIVE To review the effects of epidural vs parenteral opioid analgesia on cesarean delivery rates. DATA SOURCES Studies were identified by searching MEDLINE from January 1966 through January 1998, the Cochrane Database of Perinatal Trials, and relevant nonindexed journals and abstracts. STUDY SELECTION We included all studies that randomized patients to epidural vs parenteral opioid labor analgesia. DATA EXTRACTION Two authors independently extracted data from 10 trials enrolling 2369 patients. Odds ratios (ORs) for categorical data, weighted mean differences (WMDs) for continuous data, and 95% confidence intervals (CIs) were calculated using a random-effects model. DATA SYNTHESIS The risk of cesarean delivery did not differ between patients receiving epidural (8.2%) vs parenteral opioid (5.6%) analgesia (OR, 1.5; 95% CI, 0.81-2.76). Epidural patients had longer first (WMD, 42 minutes; 95% CI, 17-68 minutes) and second (WMD, 14 minutes; 95% CI, 5-23 minutes) labor stages. While epidural patients were more likely to have instrumented delivery (OR, 2.19; 95% CI, 1.32-7.78), they were no more likely to have instrumented delivery for dystocia (OR, 0.68; 95% CI, 0.31-1.49). After epidural analgesia, neonates were less likely to have low 5-minute Apgar scores (OR, 0.38; 95% CI, 0.18-0.81) or to need naloxone (OR, 0.24; 95% CI, 0.07-0.77). Women receiving epidural analgesia had lower pain scores during the first (WMD, -40 mm on a 100-mm scale; 95% CI, -42 to -38 mm) and second (WMD, -29 mm; 95% CI, -38 to -21 mm) stages of labor. The odds of dissatisfaction were lower with epidural analgesia (OR, 0.25; 95% CI, 0.20-0.32). CONCLUSIONS Epidural labor analgesia is not associated with increased rates of instrumented vaginal delivery for dystocia or cesarean delivery. Patients receiving epidural analgesia have longer labors. Patient satisfaction and neonatal outcome are better after epidural than parenteral opioid analgesia.