As an addendum to my question, I would also like your experts to weigh in on what the fetal survivability rate might be, given proper and timely treatment.

Roberta Gold
Encino, CA

The benefit and role of antithrombotic therapy in the prevention of placental mediated pregnancy complications in women with thrombophilia remains controversial.

First, as outlined above, the evidence of an association/causal role for hereditary thrombophilia in these disorders is not strong. Second, trial results have been mixed. One study (Gris et al. Blood 2004) suggested that recurrent late loss in women with the factor V Leiden, prothrombin gene mutation, or protein S deficiency could be reduced by about 60% with low molecular weight heparin (LMWH) prophylaxis compared with aspirin (frequency of life birth 86% vs 29%). However, this study has some important limitations and over the years less importance has been placed on the results. A subgroup analysis of the ALIFE Trial (Kandoorp et al. N Engl J Med 2010) showed no benefit to the use of LMWH plus aspirin, or aspirin in women with recurrent pregnancy losses and thrombophilia. So, at this juncture, there is no general recommendation for the use of LMWH in this setting.

The role of LMWH prophylaxis (added to aspirin) for prevention of other placental mediated pregnancy complications in women with hereditary thrombophilia remains controversial as well, with some studies showing no benefit and some showing a 10% relative risk reduction. Again, there is no consensus on the use of LMWH here.

Studies in women with antiphospholipid antibodies and a history of recurrent pregnancy losses appear to benefit from the combination of aspirin and prophylactic heparin or LMWH, although the degree of benefit varies between studies (from no benefit to a reduction in the risk of subsequent loss from 60% to 20%). 

Associate Professor, Department of Medicine McMaster University  
Director, Division of Hematology & Thromboembolism
Discipline Director for Hematology in Laboratory Medicine