Epidural analgesia during labor is an effective pain reliever that has become more commonly used. Despite wide acceptance of this use, the timing of epidural placement remains controversial, with conflicting reports on the risk for subsequent cesarean deliveries and the length of the latent phase of labor. Because of these concerns, the American College of Obstetricians and Gynecologists (ACOG) recommended using other forms of analgesia in nulliparous women until they reach dilatation of 4 to 5 cm. However, some institutions did not follow these guidelines for all women in labor, so ACOG released a follow-up report recommending that maternal request is a sufficient indication for epidural analgesia during labor and that it should not be denied on the basis of cervical dilatation. To develop better information about epidural analgesia, Vahratian and colleagues compared the effect of early epidural analgesia with that of early intravenous analgesia on labor progression.

In a retrospective analysis of obstetric data from one military medical center, including singleton, nulliparous term pregnancies with a spontaneous labor, the researchers analyzed two groups of participants. The first group included women who gave birth before a policy change that made epidural analgesia available on demand. In this group, 1 percent had epidural analgesia, while 98 percent had intravenous analgesia. The second group included women whose labor occurred after the policy change, of whom 92 percent received epidural analgesia and 8 percent received intravenous analgesia. Early analgesia was defined as that given while the patient was dilated to no more than 4 cm. As a measure of labor progression, the median duration of labor by each centimeter of dilation was computed. The study compared this and other factors in both groups.

There were 223 pregnancies in the first group and 278 pregnancies in the second group. When adjustments of confounders were made, the only period of labor that had a slower progression among women in the epidural group compared with the intravenous group was from 4 to 5 cm (see accompanying table). The intravenous group went from 4 to 5 cm in an average of 77 minutes, while the epidural group’s time was 130 minutes. There were no significant differences in the remainder of the active phase of cervical dilatation between the two groups.

The proportion of cesarean deliveries remained the same (18 percent) in both groups. In the epidural group, the use of outlet forceps or vacuum extraction increased from 10 to 14 percent, and the use of mid to low forceps or vacuum extraction decreased from 14 to 10 percent.

The authors conclude that it is unnecessary to withhold epidural analgesia before 4 cm of cervical dilatation is achieved. In their study, the only difference in labor progression between epidural and intravenous analgesia was at 4 to 5 cm and not in the early phase of labor.