Imbalanced Folate and Vitamin B12 in the Third Trimester of Pregnancy and its Association with Birthweight and Child Growth up to 2 Years

Scope Folic acid supplementation during pregnancy may lead to an imbalance when vitamin B12 intake is low (folate trap) and may affect child's growth. Methods The authors study the association between third trimester maternal intakes of folate and B12 and birthweight and postnatal growth of 2632 infants from the KOALA Birth Cohort Study. Plasma vitamin biomarkers are measured in 1219 women. Results Imbalanced total intakes (folate > 430 mu g day(-1) combined with B12 < 5.5 mu g day(-1)) are not associated with birthweight [beta adj (95% CI) = -14.87 (-68.87, 39.13)] compared with high intakes of both. Imbalanced intake is associated with a lower z score of weight at 1-2 years [beta adj = -0.14 (-0.25, -0.03)]. Having red blood cell folate > 745 nmol L-1 and plasma B12 < 172 pmol L-1 is not associated with birthweight [beta adj = -7.10 (-97.90, 83.71) g]. Maternal dietary B12 intake [beta adj = -9.5 (-15.6, -3.3)] and plasma methylmalonic acid [beta adj = 234 (43, 426)] are associated with birthweight. Conclusion Low maternal dietary B12 intake and elevated methylmalonic acid rather than imbalanced vitamins are associated with higher birthweight, suggesting that low maternal B12 can predispose the infants for later obesity