Objective: To examine the relationship of infertility to recurrent fetal loss in patients who were vitamin B12 deficient.

Study design: The obstetric histories of 14 patients presenting with 15 episodes of vitamin B12 deficiency were analyzed. Infertility (two to eight years) had been present in four episodes, and recurrent fetal loss was a feature in 11.

Results: In six episodes, periods of recurrent fetal loss were followed by periods of infertility greater than one year.

Conclusion: Hypercoagulability due to raised homocysteine levels may lead to fetal loss when vitamin B12 deficiency first develops. A more prolonged deficiency results in infertility by causing changes in ovulation or development of the ovum or changes leading to defective implantation.