Maternal and fetal plasma levels of pyridoxal phosphate at term: Adequacy of vitamin B6 supplementation during pregnancy

Abstract

The effect of different amounts of vitamin Be supplementation during pregnancy on maternal and fetal plasma levels of pyridoxal phosphate (PLP) at term has been studied. Ten of I3 subjects given 2 to 2.5 mg. of vitamin Bs daily exhibited plasma PLP levels lower than 4.7 ng. per milliliter (the lower limit of normal for nonpregnant subjects). In contrast, only 4 of II subjects given a supplement of I0 mg. of vitamin Bs daily had plasma PLP less than this value. The mean plasma PLP level (64.4 ng. per milliliter) of I0 cord blood samples from newborn infants whose mothers exhibited plasma PLP levels greater than 4.7 ng. per milliliter was significantly higher (P < 0.005) than that (34.2 ng. per milliliter) from I4 newborn infants whose mothers had abnormally lowered plasma PLP concentrations. In cord plasma, an average venous-arterial gradient of I0.6 ng. per milliliter was observed, indicating that the fetus retains and/or degrades PLP. These results suggest that more than 2 to 2.5 mg. of vitamin B6 supplement daily is required for most pregnancies to restore normal vitamin Bs nutrition in the mother and, perhaps, also in the fetus.