Pyridoxal phosphate and hypertensive disorders of pregnancy.

Pyridoxal phosphate (vitamin B6) concentrations in peripheral and cord blood obtained at the time of delivery were measured in 30 women. The average plasma concentration in nine women with normal pregnancy was 4.3 ng. per milliliter; in 10 women with pre-eclampsia, 3.3 ng. per milliliter; and in nonpregnant women, 17 ng. per milliliter. The average cord blood plasma concentration of normal infants was 28.4 ng. per milliliter, whereas that of infants of pre-eclamptic mothers was 12.2 ng. per milliliter. This twofold difference in the cord plasma concentrations was statistically significant (p smaller than 0.001). Pyridoxal phosphate concentrations in the infants' cord plasma were increased in all pregnancies studied by administration of pyridoxine either orally or intravenously. These findings together with other data, demonstrating (1) that B6 deficiency during pregnancy may lead to abnormal neurologic development in experimental animals and (2) that brain development in infants of toxemic mothers may be retarded, suggest that dietary supplementation with vitamin B6 should be instituted in women at high risk for development of toxemia of pregnancy.