Effect of epidural analgesia on operative vaginal birth rate.

The aim of the study was to investigate if epidural analgesia may affect the operative vaginal birth rate. An observational study was carried out on 1,158 in low-risk patients who delivered vaginally; 46.9% of these patients underwent epidural analgesia using different doses and drugs. Overall, epidural analgesia enhanced the probability of vacuum delivery (OR 2.70 95% CI 1.88-3.89, p < 0.001). Vacuum application was increased about seven times by administration of fentanyl alone at the first dose, while it was reduced if ropivacaine was added to fentanyl. In patients undergoing epidural analgesia, increasing the amount of ropivacaine at the first dose reduced the probability of vacuum delivery (OR 0.82; 95% CI 0.67-1.00, p = 0.05). Moreover, increasing the number of top-ups reduced the probability of vacuum delivery (OR 0.49 95% CI 0.27-0.93, p = 0.029) and the time of the second stage of labor. On the other hand, increasing time from the first dose of epidural to the last top-up increased the risk of operative vaginal delivery (OR 1.33 95% CI 1.03-1.72, p = 0.031) and the time of the second stage of labor. Epidural analgesia seems to favor spontaneous delivery when it is properly carried on.