Vitamin B12 status in pregnant women and their infants in South India

BACKGROUND/OBJECTIVES: Vitamin B-12 deficiency during pregnancy has been associated with increased risk of adverse perinatal outcomes. However, few studies have investigated the burden and determinants of vitamin B-12 status in young infants. This study was conducted to determine the associations between maternal and infant vitamin B-12 status. SUBJECTS/METHODS: Pregnant women participating in a vitamin B-12 supplementation trial in Bangalore, India, were randomized to receive vitamin B-12 (50 mu g) or placebo supplementation daily during pregnancy through 6 weeks postpartum. All women received 60 mg of iron and 500 mu g of folic acid daily during pregnancy, as per standard of care. This prospective analysis was conducted to determine the associations between maternal vitamin B-12 biomarkers (that is, plasma vitamin B-12, methylmalonic acid (MMA) and tHcy) during each trimester with infant vitamin B-12 status (n = 77) at 6 weeks of age. RESULTS: At baseline (<= 14 weeks of gestation), 51% of mothers were vitamin B-12 deficient (vitamin B-12 < 150 pmol/l) and 43% had impaired vitamin B-12 status (vitamin B-12 < 150 pmol/l and MMA > 40.26 mu mol/l); 44% of infants were vitamin B-12 deficient at 6 weeks of age. After adjusting for vitamin B-12 supplementation, higher vitamin B-12 concentrations in each trimester were associated with increased infant vitamin B-12 concentrations and lower risk of vitamin B-12 deficiency in infants (P < 0.05). After adjusting for vitamin B-12 supplementation, infants born to women with vitamin B-12 deficiency had a twofold greater risk of vitamin B12 deficiency (P < 0.01). Higher maternal folate concentrations also predicted lower risk of vitamin B-12 deficiency in infants (P < 0.05). Impaired maternal vitamin B-12 status, which combined both circulating and functional biomarkers, was the single best predictor of infant vitamin B-12 status. CONCLUSIONS: Impaired maternal vitamin B-12 status throughout pregnancy predicted higher risk of vitamin B-12 deficiency in infants, after adjusting for vitamin B-12 supplementation. Future interventions are needed to improve vitamin B-12 status periconceptionally, and to ensure optimal vitamin B-12 status and health outcomes in pregnant women and their children.