Comparison of the labor curves with and without combined spinal-epidural analgesia in nulliparous women- a retrospective study.

Background: Neuraxial labor analgesia is known to increase the rate of instrumental delivery and prolong the second stage of labor; however, there is no standard method to evaluate the progress of labor under analgesia. Friedman curve is considered the gold standard for evaluating the progress of labor. However, it included not only neuraxial labor analgesia but also labor without analgesia. Thus we compared the labor curves of primiparous women undergoing labor with and without neuraxial labor analgesia, to understand the progress of labor in both groups and to arrive at a standard curve to monitor the progress of labor under neuraxial analgesia.

Methods: Primiparous women with cephalic singleton pregnancies who delivered at term from 2016 to 2017 were included. Two hundred patients who opted for combined spinal-epidural (CSE) labor analgesia were included in the CSE group and 200 patients who did not undergo CSE were included in the non-CSE group. In all, 400 cases were examined retrospectively. The evaluation parameters were cervical dilation and fetal station, and we calculated the average value per hour to plot the labor curves.

Results: The labor curve of the non-CSE group was significantly different from the Friedman curve. In the CSE group, the time from 4 cm dilation of the cervix to full dilation was 15 h; in addition, the speed of cervical dilation was different from that in the non-CSE group. The progress of labor in the CSE group was faster than that in the non-CSE group during the latent phase; however, the progress in the CSE group was slower than that in the non-CSE group during the active phase.

Conclusions: Neuraxial labor analgesia results in early cervical dilation and descent of the fetal head; thus, appropriate advance planning to manage the delivery may be essential.