Biochemical indexes of the B vitamins in cord serum are predicted by maternal B vitamin status.

BACKGROUND The concentration of total homocysteine (tHcy) is higher in newborns than in older children. Vitamin B-12 is the major determinant of tHcy in newborns. Maternal status of folate, vitamin B-12, and vitamin B-6 during pregnancy may affect the biochemical markers of these micronutrients in newborns. OBJECTIVE Our objective was to study the relation between concentrations of the metabolites and B vitamins in maternal sera and concentrations in the umbilical venous blood of the corresponding newborns. DESIGN We studied healthy pregnant women at the time of labor who were expecting healthy, full-term, appropriate-birth-weight babies. Samples were available from 82 mother-infant pairs. RESULTS Concentrations of B vitamins were higher in cord samples than in maternal blood (folate, 2-fold; vitamin B-12, 1.5-fold; and vitamin B-6, 6-fold). Concentrations of cystathionine and methylmalonic acid (MMA) were also higher in the infants than in the mothers (x +/- SD: cystathionine, 462 +/- 189 and 343 +/- 143 nmol/L; MMA, 353 +/- 144 and 233 +/- 110 nmol/L). No significant differences in tHcy concentrations were observed between fetal and maternal samples. Concentrations of vitamin B-12 did not differ significantly between mothers of infants from different quartiles of cord MMA. Higher fetal MMA concentrations were related to higher maternal MMA and vitamin B-12 concentrations and lower fetal concentrations of vitamin B-12. Fetal concentrations of cystathionine were predicted by maternal cystathionine, gestational age, fetal vitamin B-6, and fetal tHcy. CONCLUSIONS Maternal concentrations of the metabolic markers of B vitamins predict values in fetal blood at delivery. Fetal tHcy concentrations were low but were predicted by the vitamin status of the mother. The effect of increasing maternal intake of vitamins B-12 and B-6 during pregnancy on the fetal concentrations of the metabolites should be investigated.