Low-molecular-weight heparin or warfarin for anticoagulation in pregnant women with mechanical heart valves: what are the risks? A retrospective observational study.

The management of anticoagulation in pregnant women with mechanical heart valves is complex. The maternal and fetal outcomes of 32 pregnancies in 15 women on three different anticoagulation regimens were compared. Anticoagulation with low-molecular-weight heparin (n=4), warfarin (n=22) and combination therapy (n=6) resulted in adverse maternal events in four (100%), three (50%) and three (14%) women, and resulted in fetal losses in one (25%), 17(77%) and three (50%) pregnancies, respectively. Whereas the rate of fetal loss in the warfarin group was high, all women in the LMWH and half of those in the combination group had serious adverse maternal events, including valve thrombosis, maternal death and postpartum haemorrhage.