[Epidural analgesia in obstetrics: is there an effect on labor and delivery?]

Epidural analgesia is routinely used in obstetrics but has been blamed for possible effects on labor that lead to greater use of instruments or conversion to cesarean delivery. We aimed to assess this possibility in a cohort of obstetric patients receiving or not receiving epidural analgesia.

Prospectively enrolled full-term obstetric patients were distributed in 2 groups according to whether they received epidural analgesia or not. We compared maternal and fetal characteristics, obstetric variables, and type of delivery between groups to record the likely causes of difficult labor and delivery and detect a possible influence of epidural analgesia.

Of a total of 602 patients, 462 received epidural analgesia and 140 did not. Epidural analgesia was related to a higher rate of use of instruments but not cesareans (P < .01) and more frequent need for oxytocin (30.7% of the epidural analgesia group vs 0% of the group receiving no epidural analgesia, P < .001). The women receiving analgesia also had a longer mean (SD) duration of the dilatation phase of labor (6.4 [4.2] hours in the epidural group vs 4.7 [3.5] hours in the no-epidural group, P < .01) and of the expulsion phase (1.0 [0.6] hours vs 0.7 [0.6] hours, respectively; P<.01). We observed no effects on the incidence of tearing, rate of episiotomy, or other variables. Predictors of instrumentation or conversion to cesarean delivery were longer duration of the first phase (odds ratio [OR] 1.2; 95% confidence interval [CI], 1.1-1.3), longer duration of the second phase (OR 2.3; 95% CI, 1.3-3.9), and maternal obesity (OR, 1.1; 95% CI, 0.9-1.2). Previous deliveries and initiation of epidural analgesia after the fetus has reached Hodge's first plane decreased risk 2.7-fold and 3.03-fold, respectively.

Although epidural analgesia has traditionally been associated with a higher incidence of difficult labor and delivery, this association was not unequivocally evident in this cohort of patients. The apparent increase seems to be attributable to such obstetric factors as longer duration of stages of labor, higher body mass index, and first delivery.