Longitudinal vitamin and homocysteine levels in normal pregnancy

Evidence of the impact of maternal nutritional status on pregnancy outcome is increasing. However, reference values for vitamin and homocysteine conce ntrations in maternal blood during normal pregnancy are scarce, and are lac king for the preconceptional period and early pregnancy. Thus, in a longitu dinal study we evaluated vitamin and homocysteine concentrations in 102 nul liparous women with an uneventful singleton pregnancy and normal outcome no t using supplements. The physiological changes in vitamin and homocysteine concentrations in blood were determined from the preconceptional period thr oughout pregnancy until 6 weeks post-partum. The vitamins evaluated compris ed retinol, thiamin, riboflavin, pyridoxal 5'-phosphate, folate in serum an d erythrocytes, vitamin B-12 and alpha -tocopherol. The plasma homocysteine concentration was also measured, considering the essential roles of folate , vitamin B-6 and vitamin B-12 in homocysteine metabolism. The concentratio ns of retinol, thiamin, pyridoxal 5'-phosphate serum folate and vitamin B-1 2 decreased during pregnancy. In contrast, the concentrations of riboflavin , alpha -tocopherol, and folate in erythrocytes increased or showed only mi nor changes. Homocysteine concentrations also remained approximately consta nt during pregnancy. These observations emphasize the importance of preconc eptional and post-partum concentrations of vitamins in the evaluation of pr egnancy-induced changes. These data have provided valuable reference values for vitamins and homocysteine before, during and after pregnancy in order to contribute to better diagnosis of maternal deficiencies and to study fur ther the relationship between maternal vitamin status and adverse course an d outcome of pregnancy.