Vitamins B12 and B6 and folate are known to have implications for pregnancy outcomes. We aimed to describe B6, B12, and folate status in pregnancy and investigate their associations with low birth weight and preterm delivery in mothers recruited from public hospitals in urban Bengaluru. Pregnant women between 18 and 45 years were included in the MAASTHI prospective cohort study. Each participant's age, socioeconomic status, and anthropometry were recorded during baseline and followed up after delivery. Blood samples were collected between the 24th and 32nd weeks of gestation and stored at -80° for analysis. B6, B12, folate, homocysteine, and methylmalonic acid (MMA) levels were analyzed in the stored samples. We found low plasma vitamin B12, folate, and B6 levels in 48.5%, 42.0%, and 10.4% of the women (n = 230), respectively. Elevated MMA and homocysteine were observed among 73.6% and 6.1% of the women, respectively. We found B6 levels were significantly associated with birth weight (β(SE) -0.002(0.0), p = 0.001) after adjusting for age, parity, adiposity, gestational diabetes, and socioeconomic status of the mother. Those with impaired folate deficiency were twice at risk (AOR 1.95 (1.29, 3.07), p = 0.002) of low birth weight. Vitamin B6 levels and impaired folate status were associated with low birth weight in the MAASTHI birth cohort.
Keywords: B12 deficiency; folic acid; low birth weight; pregnancy; preterm delivery; vitamin B6.