Objective: To describe experience with 41 pregnancies treated with the low-molecular-weight heparin enoxaparin. Methods: The medical charts of 34 women (a total of 41 pregnancies) treated between January 1992 and March 1995 with the low-molecular-weight heparin enoxaparin were reviewed. Most patients (87.5%) received one daily 40-mg injection. In all cases, treatment was continued throughout tabor, delivery, and the immediate postpartum period. Results: Therapy was administered for 5-280 days (median 91). One case of a thromboembolic event was recorded during treatment. No systemic or local side effects were reported. During pregnancy, only one patient had mild vaginal bleeding, which resolved spontaneously while therapy was continued. There was no excessive intrapartum bleeding in any of these patients, whether delivered vaginally or abdominally. During treatment, 19 of the 34 patients underwent 24 surgical procedures, including 13 cesarean deliveries, without excessive bleeding. Epidural anesthesia was used during labor in nine of the patients, with no specific complications. The corrected perinatal mortality rate, (ie, the rate of fetal death after 24 weeks' gestation plus neonatal death, excluding a neonate with multiple anomalies) for those neonates delivered after 24 weeks' gestation was 2.7%. There were no cases of intraventricular hemorrhage in any of the neonates. Conclusion: This preliminary series, the largest reported to date, demonstrates the relative safety and efficacy of low-molecular-weight heparin therapy in pregnancy and delivery.