High rate of maternal vitamin B12 deficiency nearly a decade after Canadian folic acid flour fortification

Vitamin B12 deficiency may be an independent risk factor for neural tube defects ( NTD). We determined the prevalence of biochemical B12 deficiency (< 125 pmol/ l) among 10 622 Ontarian women aged 15 - 46 years who underwent concomitant testing of serum bhCG and B12 9 years after the implementation of Canadian folic acid flour fortification. The overall prevalence of biochemical B12 deficiency was 7.4%. Relative to non- pregnant women, the adjusted odds ratio ( 95% confidence interval) of biochemical B12 deficiency was 0.78 ( 0.60 - 1.0) among women pregnant 28 days gestation or less and was 1.4 ( 1.1 - 1.8) after 28 days gestation. About 1 in 20 women may be deficient in B12 in early pregnancy. The impact on maternal and fetal well- being, including preventable NTD, should be considered.