The 5, 10 methylenetetrahydrofolate reductase C677T mutation and risk of fetal loss: a case series and review of the literature.

Background: The true relationship between methylenetetrahydrofolate reductase C677T homozygosity and risk of recurrent spontaneous abortion is unknown, and it is unclear if women with these mutations should be anticoagulated during pregnancy.

Objectives: We report a series of 8 patients with this issue and review the current literature.

Methods: 8 patients (3 of whom were actively pregnant) were referred with histories of spontaneous fetal loss; hypercoaguability work-ups revealed each were homozygous for the MTHFR C677T mutation without other thrombophilias.

Results: In the 3 women who have conceived, treatment with LMW heparin during pregnancy led to two full-term births and one additional pregnancy without complication. For the 5 who have not, we recommended treatment with LMW heparin upon conception.

Conclusion: We provide evidence to support the relationship between MTHFR C677T mutations and recurrent fetal loss, and to suggest that anticoagulation of these patients during pregnancy can lead to a successful pregnancy outcome.