American Journal of Clinical Nutrition, Vol 24, 704-708, Copyright © 1971 by The American Society for Clinical Nutrition, Inc.

Abnormal tryptophan metabolism in pregnancy and with the oral contraceptive pill. II. Relative levels of vitamin B₆-vitamers in cord and maternal blood

¹ From the Department of Biochemical Nutrition, Hoffmann-La Roche Inc., Nutley, New Jersey. This work was partially done in the Departments of Biochemistry and Medicine at the Upstate Medical Center, State University of New York, at Syracuse

Paired samples of maternal and cord blood plasma were analyzed for the three vitamin B₆-vitamers and for total vitamin B₆ content. Also, the erythrocytes from the same blood samples were analyzed for oxalacetic and pyruvic aminotransferase activity.

Levels of vitamin B₆-vitamers in plasma and of erythrocyte aminotransferase activity were at least twice as high in cord blood as in maternal blood. The compartmentalization of vitamin B₆ in the fetus may have been due to an active placental transport mechanism, or may have reflected increased numbers of binding sites in fetal tissues due to increased levels of pyridoxine-requiring enzymes. Either of these mechanisms might result in partial depletion of the mother-host for vitamin B₆. The findings also serve to partially explain the high incidence of abnormal tryptophan load tests in pregnancy.