Does epidural anesthesia affect the course of labor and delivery?

The progress of labor ideally leads to a normal, spontaneous, vaginal delivery. Many factors--maternal, fetal, obstetrical and anesthetic--may collectively contribute to delaying or precluding an ideal outcome. Adverse outcomes of labor and delivery must be clearly defined in terms of maternal, fetal, or neonatal morbidity or mortality, and should be distinguished from abnormal data (such as fetal heart rate, duration of labor, and incidence of low forceps deliveries) that are only indirectly related to outcome. Epidural anesthesia is not a singular phenomenon. Variations and subtle nuances in the administration of epidural anesthesia create a vast array of potential anesthetic regimens. To discover the anesthetic methods that provide excellent analgesia with no adverse effects on the course of labor is an ideal goal that has not yet been achieved. To approach this goal, the answers to several questions are needed. Are study patient groups adequately matched for risk factors? Are obstetrical practices well-defined with respect to elective versus indicated use of instrumental or cesarean delivery methods? Do the risks of instrumental delivery outweigh the benefit of perineal analgesia associated with epidural anesthesia? Is it possible to provide optimal analgesia throughout stage two labor without tending to increase the risk of instrumental delivery? Can delayed pushing during stage two labor increase the probability of spontaneous vaginal delivery with continuous epidural anesthesia? Well-controlled clinical trials and refinements in both anesthetic and obstetric techniques are necessary to resolve such issues so that every parturient (and fetus) may undergo a safe and painless delivery.