Epidural analgesia is used as a pain management tool during labor. Studies evaluating the impact of epidural analgesia on the risk of cesarean delivery have had conflicting results. A recent review stated that epidural analgesia does not increase the risk of cesarean delivery. Another issue with epidural analgesia is when to initiate the treatment. Initial studies have implied that there may be a heightened risk of cesarean delivery if the epidural analgesia is initiated before 5 cm of cervical dilatation. Other studies, however, have found no difference between early initiation of epidural analgesia and late initiation. Ohel and colleagues evaluated the effect of the timing of epidural analgesia on the risk of cesarean delivery in nulliparous patients.

This randomized study included 449 nulliparous women who were in active labor, with at least two painful contractions within 10 minutes. To participate, the women were required to have had at least 36 weeks of gestation, nulliparity, established labor, and cervical effacement of at least 80 percent and dilatation of 3 cm or less. Those with cervical dilatation greater than 3 cm, estimated fetal weight of more than 4,000 g (8 lb, 13 oz), medical complications, or an abnormal admission fetal heart rate tracing were excluded. The primary outcome was the risk of cesarean delivery.

The participants were randomized to receive early (up to 3 cm dilatation) or late (4 to 5 cm dilatation) epidural analgesia. Additional data were collected on the patients’ sense of control during labor, satisfaction with the epidural analgesia, and preference about the timing of the analgesia.

Of the 449 women included in the study, 221 were in the early epidural analgesia group. The mean dilatations were 2.4 cm in this group and 4.6 cm in the late group. The rates of cesarean delivery were 13 percent in the early group and 11 percent in the late group; the authors concluded this difference was not statistically significant.

From the start of the randomization, the mean duration of the first stage of labor was 5.9 hours in the early group compared with 6.6 hours in the late group (P = .04). Seventy-eight percent of the patients in the late group stated they would prefer early epidural analgesia for their next delivery.

The authors concluded that earlier initiation of epidural analgesia during active labor did not result in an increased risk of cesarean delivery compared with late initiation. They add that early epidural analgesia was associated with a shorter duration of labor and was preferred by most of the women in the study.