CALCIUM METABOLISM IN PREGNANCY AND IN THE NEWBORN

Abstract

Summary Various aspects of calcium metabolism were studied in Negro, Caucasian and Asian mothers and their infants. There was an increase in circulating parathyroid hormone in pregnancy and umbilical cord plasma levels were usually as high as those in maternal plasma at delivery indicating that parathyroid hormone crossed the placental barrier. This increase in circulating parathyroid hormone probably reflects calcium depletion of the mother by the fetus and was most marked in women whose diet had a low vitamin D, low calcium and high phytic acid phosphorus content. Transient neonatal hypocalcaemia was most common in the infants of Asian women, even when these were breast fed, and it was these women whose antenatal serum calcium, phosphorus and heat labile alkaline phosphatase values suggested that they had maximum parathyroid stimulation. Bakwin (1937) suggested that high circulating levels of parathyroid hormone cause hypoplasia of the fetal parathyroid glands with a fall of serum calcium in the neonatal period; our results support this theory.