Background: Low concentrations of local anesthetics (LCLAs) are increasingly popular for epidural labor analgesia. The effects of epidural analgesia with low concentrations of anesthetics on the duration of the second stage of labor and the instrumental birth rate, however, remain controversial. A systematic review was conducted to compare the effects of epidural analgesia with LCLAs with those of nonepidural analgesia on obstetric outcomes.
Methods: The databases of PubMed, Embase, and the Cochrane controlled trials register were independently searched by 2 researchers, and randomized controlled trials that compared epidural labor analgesia utilizing LCLAs with nonepidural analgesia were retrieved. The primary outcomes were the duration of the second stage of labor and the instrumental birth rate; secondary outcomes included the cesarean delivery rate, the spontaneous vaginal delivery rate, and the duration of the first stage of labor.
Results: Ten studies (1809 women) were included. There was no significant difference between groups in the duration of the second stage of labor (mean difference = 5.71 minutes, 95% confidence interval [CI], -6.14 to 17.83; P = .36) or the instrumental birth rate (risk ratio [RR] = 1.52, 95% CI, 0.97-2.4; P = .07). There was no significant difference between groups in the cesarean delivery rate (RR = 0.8, 95% CI, 0.6-1.05; P = .11), the spontaneous vaginal delivery rate (RR = 0.98, 95% CI, 0.91-1.06; P = .62), or the duration of the first stage of labor (mean difference = 17.34 minutes, 95% CI, -5.89 to 40.56; P = .14).
Conclusions: Compared with nonepidural analgesia, epidural analgesia with LCLAs is not associated with a prolonged duration of the second stage of labor or an increased instrumental birth rate. The results of this meta-analysis are based on small trials of low quality. These conclusions require confirmation by large-sample and high-quality trials in the future.