Impact of Epidural Analgesia on Labor: Length of Labor, Operative Vaginal Delivery Rate and Occiput Posterior

摘要

Epidural analgesia (EA) is widely used as labor analgesia. It has been reported that EA can slow down the course of labor and increase the risk of operative vaginal delivery. Slower course of labor can lead to an increased risk of abnormal fetal heart rate (FHR). Some studies have also demonstrated an increase in occiput posterior position of the fetal head at delivery if EA is used. It represents a mechanism that may contribute to the lower rate of spontaneous vaginal delivery. Aim of study. To evaluate the impact of EA on the length of labor and the rate of operative vaginal delivery, and to determine whether EA increases the rate of occiput posterior of the fetal head at delivery Material and methods. We carried out a retrospective case-control study based on clinical records from parturients admitted to Riga Maternity Hospital in 2013. Parturients were divided into two groups: case group comprised parturients who had EA, while parturients of control group did not have EA. Groups were further subdivided into primiparas and multiparas and comparisons were made according to parity. We excluded parturients who had obstructed labor, pathological labor, induction of the labor, history of C-section and significant anomaly of the fetus. Results. A total of 832 parturients were included in the study, 304 in EA group (220 primiparas and 84 multiparas) and 528 in control group (257 primiparas and 271 multiparas). Primiparas of EA group had longer latent phase of the first stage of labor in comparison to primiparas of control group (p=0.001), while multiparas of EA group had longer first stage (p=0.031) of labor and longer latent phase of labor (p<0.001) than their respective controls. Vacuum extraction was used in 1.27% of all deliveries with EA. Moreover, vacuum extraction was used only in primiparas an there was no statistically significant difference between EA group primiparas and control group primiparas (1.7% vs. 1.2%, p=0.593). EA did not increase the rate of occiput posterior positon of fetal head. However, primiparas with EA and occiput posterior were more likely to have an abnormal FHR tracing in comparison to primiparas with EA and without occiput posterior position of fetal head (40% vs. 9.8%, p=0.029; RR=4.09, 95% CI 1.3-12.9). There was no statistically significant link between occiput posterior position and abnormal FHR tracing in control group primiparas. Conclusion. EA does not increase the likelihood of operative vaginal delivery. However, parturients with EA have longer latent phase of the first stage of labor. Risk for occiput posterior at delivery is not increased in labor with EA. However, the risk for abnormal FHR among primiparas who receive EA is increased in case of occiput posterior position of the fetal head.