Mutations in the factor V, prothrombin and MTHFR genes are not risk factors for recurrent fetal loss

Recurrent fetal loss, defined as the occurrence of three or more consecutive spontaneous abortions regardless of previous live birth, is a condition that affects about 2% of all reproductive-aged women. The role of gene mutations in recurrent pregnancy loss is not fully understood. The present research examined the relationship between factor V Leiden, factor V HR2, prothrombin G20210A and MTHFR and recurrent fetal loss in a case-control study.

Women aged 22-45 with a history of three or more fetal losses, being seen at a perinatal medicine clinic in New Jersey or Georgia, were eligible as cases. Overall, the study consisted of 60 women with three or more fetal losses and 92 women with at least one successful pregnancy.

Factor V HR2 and MTHFR were not related to recurrent fetal loss. The prothrombin G20210A mutation appeared to confer an elevation in risk but the association was based upon small numbers and was not statistically significant (OR 4.8, 95% CI 0.50-47.2). Cases were 90% less likely to have the factor V Leiden mutation than controls (OR 0.10, 95% CI 0.01-0.81).

Our study did not demonstrate that women who are carriers of the factor V, prothrombin, or MTHFR mutations are at higher risk of recurrent fetal loss than women without these mutations. In regards to factor V Leiden, the prevalence in our cases (1.7%) was not statistically different from the known population prevalence of 5%. However, the high prevalence in our controls (14%) was unusual. Factor V Leiden may protect against bleeding in early pregnancy.