Role of Vitamin B12 Supplementation During Pregnancy and Postpartum to Reduce Nutritional Anemia and Improve Immunity in Bangladeshi Women and Their Infants

Nutritional anemia is a major public health problem among children and women in developing countries. Despite ongoing national program of supplementing pregnant women with iron-folate, prevalence of anemia is 39% among pregnant women and 78% among infants in Bangladesh. Vitamin B12 deficiency is a more prevalent cause of megaloblastic anemia than folate in many developing countries. This data raises the interest to address the role of vitamin B12 deficiency in nutritional anemia. Low dietary intake of animal products, a predominant source of vitamin B12 may cause anemia. Besides maintaining normal erythropoiesis, B12 is essential for immune function. However, no studies have evaluated the effect of maternal B12 supplementation on reduction of anemia and improving immunity of their infants. The investigators hypothesize that vitamin B12 supplementation plus iron-folate during pregnancy and 3-mo postpartum would: (a) Decrease anemia among mothers and infants; (b) Improve vaccine specific cellular and humoral immune responses among mothers; (c) Improve vaccine specific immunity in infants by passive transfer; (d) Improve DNA methylation and one-carbon metabolism in mother-child pairs; (e) Reduce antenatal/postnatal depression. Results from this study will guide and provide support to the policy makers to identify effective strategies to reduce nutritional anemia in population at risk.

The investigators aim to conduct a double-masked placebo controlled trial to investigate the added effect of vitamin B12 on the iron-folate supplementation among pregnant women. Anemic (Hb level <11.0 g/dl) mothers at 11-14 weeks of gestation will be randomized into two groups: supplement group will receive 250 ug vitamin B12 plus 400 ug folate and 60 mg iron; placebo group will receive folate and iron only. This daily supplementation will continue up to 3-mo postpartum. At 26-28 wk of gestation mothers will be given inactivated influenza vaccine. Data on anthropometric indices of mothers and children, birth size, infant growth and morbidity (mothers and children) throughout the study period will be recorded. 24-h dietary recall data will be collected from the mothers bimonthly throughout the study. Biochemical indicators of anemia including Hb, vitamin B12, ferritin, folate and α-glycoprotein (AGP) will be assessed in plasma of mothers (pre- and post-supplementation) and infants (cord blood and 3-months). Additional measurements include serum transferrin receptor (sTfR) in plasma and methyl malonic acid (MMA) and total homocysteine (tHcy) in the urine of mothers. Plasma vaccine specific antibody responses will be measured in mothers (pre- and post supplementation) and in infants (cord blood and 3-months). In breast milk, B12, folate and s-IgA will be determined. Genetic polymorphism (one-carbon metabolism) and DNA methylation will be studied in mothers and in cord blood.