Clinical B12 deficiency in one case of recurrent spontaneous pregnancy loss

Moderate hyperhomocysteinaemia (HHcy) and the homozygous mutation C677T in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene are associated with increased risk of recurrent pregnancy loss. This HHcy is currently reported as a consequence of folate rather than of vitamin B12-deficient status. We describe one case of recurrent early pregnancy loss with HHcy caused by B12 deficiency. A 38-year old woman had four episodes of early spontaneous pregnancy loss. Biological data: no haemostasis disorders, HHcy (25.9 micromol/l), normal folate (5 ng/ml), B12 deficiency (< 150 pg/ml) and the MTHFR C677T homozygote genotype. A bone marrow biopsy gave evidence of moderate megaloblastosis. Parenteral B12 therapy led to normal homocysteine level within 2 months and to a successful pregnancy. In conclusion, vitamin B12 deficiency is one of the causes of recurrent pregnancy loss associated with HHcy, and serum B12 should be measured systematically in this circumstance.