Over the last several years, there has been an increased interest in evaluating patients with recurrent pregnancy loss for the presence of thrombophilia. Thrombophilia literally means “thrombosis-loving”; a thrombosis is a blood clot. All humans exist in a balance between bleeding and blood clotting. Genetic conditions such as hemophilia leave affected individuals open to complications arising from excessive bleeding. Similarly, people who have genetic predispositions to blood clotting can be at risk for problems ranging from blood clots in the lung (pulmonary embolus) or leg (deep vein thrombosis), to an increased risk of miscarriage or poor pregnancy outcomes, including intrauterine fetal demise and intrauterine growth retardation.

Typical tests for thrombophilia include assessment of Factor V Leiden, prothrombin II, proteins C and S, antithrombin III, and the methyltetrahydrofolate reductase (MTHFR) enzyme. All of these, except MTHFR, are genetic enzyme deficiencies that cause the affected person to have a propensity toward blood clot formation; these conditions are often treated with pediatric aspirin and heparin (usually Lovenox).

People with an MTHFR mutation may be at higher risk for blood clot formation (and miscarriage) if they also have elevated levels of homocystine, a metabolic by-product of folic acid metabolism. People who are positive for two copies of an MTHFR enzyme mutation are best treated with vitamin supplementation consisting of folic acid, vitamin B6, and vitamin B12. Several preparations have been specifically formulated for these individuals (Foltx or Folgard). Women with thrombophilia are probably best evaluated by a hematologist to review the potential need for anticoagulation before, during, and following any pregnancy. Recent data has cast some doubt on the connection between thrombophilia and pregnancy loss, but most REs continue to test for these conditions and await definitive research.