Predicting early epidurals: association of maternal, labor, and neonatal characteristics with epidural analgesia initiation at a cervical dilation of 3 cm or less

BACKGROUND Retrospective studies have associated early epidural analgesia with cesarean delivery, but prospective studies do not demonstrate a causal relationship. This suggests that there are other variables associated with early epidural analgesia that increase the risk of cesarean delivery. This study was undertaken to determine the characteristics associated with early epidural analgesia initiation. METHODS Information about women delivering at 37 weeks or greater gestation with epidural analgesia, who were not scheduled for cesarean delivery, was extracted from the McGill Obstetric and Neonatal Database. Patients were grouped into those who received epidural analgesia at a cervical dilation of ≤3 cm and >3 cm. Univariable and multivariable logistic regression was used to determine the maternal, neonatal, and labor characteristics that increased the risk of inclusion in the early epidural group. RESULTS Of the 13,119 patients analyzed, multivariable regression demonstrated odds ratios (OR) of 2.568, 5.915 and 10.410 for oxytocin augmentation, induction, and dinoprostone induction of labor (P < 0.001). Increasing parity decreased the odds of early epidural analgesia (OR 0.780, P < 0.001), while spontaneous rupture of membranes (OR 1.490) and rupture of membranes before labor commenced (OR 1.288) were also associated with early epidural analgesia (P < 0.001). Increasing maternal weight (OR 1.049, P = 0.002) and decreasing neonatal weight (OR 0.943, P < 0.001) were associated with increasing risk of early epidural analgesia. CONCLUSION Labor augmentation and induction, nulliparity, rupture of membranes spontaneously and before labor starts, increasing maternal weight, and decreasing neonatal weight are associated with early epidural analgesia. Many of these variables are also associated with cesarean delivery.