OBJECTIVE This study was designed to determine the relationship between maternal position and the incidence of prolonged decelerations after epidural bupivacaine or intrathecal sufentanil analgesia for labor. METHODS Laboring, healthy, term parturient women, with reassuring fetal heart rate tracings, requesting either epidural (n = 145) or intrathecal (n = 160) analgesia were randomly assigned to lie either supine with measured 30-degree left uterine displacement (n = 136) or in the left lateral decubitus position (n = 145). Patients received either intrathecal sufentanil, 10 microg, or epidural 0.25% bupivacaine, 13 mL. An obstetrician, unaware of patient position or type of anesthesia, examined the fetal heart rate tracings. RESULTS No demographic differences were noted among the groups. Prolonged decelerations occurred with equal frequency after epidural bupivacaine and intrathecal sufentanil (3.9%). Prolonged decelerations were not related to maternal position. No emergency cesarean deliveries were performed as a result of prolonged decelerations. Prolonged decelerations correlated with the frequency of contractions before induction of analgesia (P < .05). Fewer fetal heart rate accelerations were noted after intrathecal sufentanil than after epidural bupivacaine (P < .005). More ephedrine was used after epidural bupivacaine (P < .001). Patients who received epidural analgesia in the left lateral position were more likely to have an asymmetric block (P < .05). CONCLUSIONS The risk of prolonged deceleration after epidural bupivacaine or intrathecal sufentanil labor analgesia is unrelated to maternal position or analgesic technique.