The incidence of poor fetal growth, both low birth weight (LBW) and intrauterine growth retardation, is quite high in developing countries and in India. Pregnant Indian women with low vitamin B12 status have a higher risk of delivering a LBW but appropriate for gestational age baby. The mechanism by which prenatal vitamin B12 status can possibly influence birth size is through epigenetic phenomena relating to the lower methylation of key regions of the genome; while folate deficiency has been shown to have an effect, vitamin B12 deficiency may also operate through this mechanism. Methionine plays a critical role in methylation of the fetal genome by providing one-carbon units through the methionine cycle and by its interaction with the micronutrient and hormonal milieu.
This proposal aims to provide a better understanding of how maternal under nutrition alter the metabolic/physiologic processes and will test nutritional therapies aimed at reducing or correcting their adverse outcomes. We hypothesized that methionine cycle kinetics, particularly transmethylation and remethylation rates, would decrease with vitamin B12 deficiency, and therefore, this study aimed to measure methionine kinetics in the 1st and 3rd trimesters of pregnancy in vitamin B12 deplete and replete pregnant women.