We studied the outcome of 41 pregnancies in an attempt to identify an appropriate and safe anticoagulant regimen for pregnant women with cardiac valve prosthesis. The cumulative number of events: (neonatal death, premature deliveries, intrauterine fetal death and spontaneous abortion) was 66.6%, 20%, 12.5% and 20% in the Coumadin, Fraxiparine, Heparin and porcine valve groups, respectively. We conclude that in pregnant women with mechanical heart valves, low molecular weight heparin therapy is a superior strategy compared to warfarin.