Objective is to examine the effect of epidural analgesia in first stage of labor on occurrence of cesarean and operative vaginal deliveries in nulliparous women and multiparous women without a previous cesarean delivery. Design of the Prospective cohort study. Prenatal care was received at 12 free-standing health centers, 7 private physician offices, or 2 hospital-based clinics; babies were delivered at a free standing birth center or at 3 hospitals, all in San Diego, CA. This study of 2,052 women used data from the San Diego Birth Center Study that enrolled women between 1994 and 1996 to compare the birthing management of the collaborative Certified Nurse Midwife-Medical Doctor Model with that of the traditional Medical Doctor Model. Main Outcome Measures of the Cesarean or operative vaginal deliveries. After adjusting for differences between women who used and those who did not use epidural analgesia in 1st stage of labor, epidural use was associated with a 2.5 relative risk (95% CI: 1.8, 3.4) for operative vaginal delivery in nulliparous women, and a 5.9 relative risk (95% CI: 3.2, 11.1) in multiparous women. Epidural use was associated with a 2.4 relative risk (95% CI: 1.5, 3.7) for cesarean delivery in nulliparous women, and a 1.8 relative risk (95% CI: 0.6, 5.3) in multiparous women. Epidural anesthesia increases the risk for operative vaginal deliveries in both nulliparous and multiparous women, and increases risk for cesarean deliveries in nulliparous more so than in multiparous women.
