The nature and management of labor pain: part II. Pharmacologic pain relief.

A group of family physicians, obstetricians, midwives, obstetric anesthesiologists, and childbirth educators attended an evidence-based symposium in 2001 on the nature and management of labor pain and discussed a series of systematic reviews that focused on methods of labor pain management. Parenteral opioids provide modest pain relief in labor, and little evidence supports the use of one agent over another. Epidural analgesia is used during labor in most large U.S. hospitals, and its use is rapidly increasing in small hospitals. Although epidural analgesia is the most effective form of pain relief, its use is associated with a longer labor, an increased incidence of maternal fever, and increased rates of operative vaginal delivery. The effect of epidural analgesia on rates of cesarean delivery is controversial. Nitrous oxide provides a modest analgesic effect, but it is used less often in the United States than in other developed nations. Paracervical block provides effective analgesia in the first stage of labor, but its use is limited by postblock bradycardia. Research is needed regarding which pain-relief options women would choose if they were offered a range of choices beyond epidural analgesia or parenteral opioids.