OBJECTIVE Labor analgesia with the combined spinal epidural approach has been associated with maternal hypotension and fetal heart rate (FHR) changes. The purpose of this study was to estimate whether prophylactic intramuscular ephedrine before combined spinal epidural prevents these complications. METHODS In a prospective double blind trial, 100 healthy patients with term singletons received intramuscular ephedrine 25 mg or placebo by random allocation before combined spinal epidural. During the first hour after analgesia, maternal heart rate, blood pressure, and need for treatment of significant hypotension were recorded. Fetal heart rate tracings for 1 hour before and for 1 hour after administration of anesthetic were evaluated. Categorical variables were compared with Fisher exact test. Continuous variables were compared with one way analysis of variance for repeated measures. P < .05 was considered significant. RESULTS Prophylactic ephedrine reduced the incidence of maternal hypotension after combined spinal epidural (P < .007). In controls, there was a significant increase in the incidence and frequency of late decelerations in the hour following combined spinal epidural compared with the previous hour (P < .005 and P < .01). Compared with controls, there was an increased incidence of fetal tachycardia in patients who received prophylactic ephedrine (P < .006), which was associated with increased FHR reactivity (P < .03). CONCLUSIONS Although prophylactic ephedrine prevents maternal hypotension and fetal late decelerations, it is associated with fetal tachycardia. The value of prophylactic ephedrine at combined spinal epidural should be weighed against potential changes in fetal heart rate patterns. METHODS I.