Fixed mini-dose warfarin for prophylaxis of thromboembolic disease in pregnancy: a safe alternative for the fetus?

Abstract

Fixed mini-dose warfarin has been used for thromboprophylaxis in high-risk nonpregnant patients with encouraging results. The usefulness of this strategy in pregnant women requires documentation of fetal safety. A woman with antithrombin III deficiency suffered a venous thrombosis during early pregnancy and could not be successfully managed long term with heparin. One milligram of warfarin daily was used for prophylaxis, and serial fetal blood samples were used to monitor the fetal coagulation status. No apparent coagulation abnormalities were demonstrated in the fetus at 33, 36, and 38 weeks' gestation. The woman suffered no further thromboses throughout the remainder of her pregnancy and puerperium. The efficacy of fixed mini-dose warfarin for prophylaxis in pregnancies at risk for thromboembolic disease will require further investigation. This fetus did not appear vulnerable to coagulation abnormalities as a consequence of the warfarin regimen.