Vitamin B12 Deficiency Increases Risk of Birth Defects

DUBLIN, Ireland—Irish researchers found deficient or inadequate maternal vitamin B12 status was associated with a significantly increased risk for neural tube defects (Pediatrics. 2009;123(3):7-923) (DOI:10.1542/peds.2008-1173).

Researchers assessed pregnancy vitamin B12 status concentrations in blood samples taken at an average of 15 weeks’ gestation from three independent nested case-control groups of Irish women within population-based cohorts, at a time when vitamin supplementation or food fortification was rare. Group one blood samples were from 95 women during a neural tube defect–affected pregnancy and 265 control subjects. Group two included blood samples from 107 women who had a previous neural tube defect birth but whose current pregnancy was not affected and 414 control subjects. Group three samples were from 76 women during an affected pregnancy and 222 control subjects. Mothers of children affected by neural tube defect had significantly lower B12 status. In all three groups, those in the lowest B12 quartiles compared with the highest, had between two and threefold higher adjusted odds ratios for being the mother of a child affected by neural tube defect. Pregnancy blood B12 concentrations of less than 250 ng/L were associated with the highest risks.

Researchers suggested women have vitamin B12 levels of more than 300 ng/L (221 pmol/L) before becoming pregnant.