One of the major tasks of fetal growth and development during pregnancy is the accretion of bone and the formation of the fetal skeleton. Bone accretion in any growing skeleton requires sufficient levels of, extracellular calcium and phosphorus.
But, calcium metabolism in human pregnancy is a complex process.
In recent years, calcium supplementation during pregnancy has been widely practiced.
The aim of this investigation was to characterize maternal and fetal adjustments in calcium metabolism by measuring blood levels of total calcium, ionized, calcium, inorganic phosphorus, albumin and calcium regulating hormones; parathyroid hormone, calcitonin and 25-hydroxyvitamin D3 in the pregnant women and fetal umbilical cords. These groups were without calcium supplementation during pregnancy.
The results were as follows;
1. The apparent decrease in maternal serum total calcium and ionized calcium levels´ were observed throughout the gestational period and their levels increased in the postpartum. Inorganic phosphorus in maternal serum was slightly decreased in the first trimester and then markedly decreased at term. In the postpartum, the level of inorganic phosphorus was elevated.
2. The increase in maternal plasma parathyroid hormone and calcitonin was observed during, pregnancy, and their elevated levels decreased in the postpartum. In contrast to the parathyroid hormone and calcitonin, maternal plasma 25-hydroxy vitamin D3 declined throughout gestation, and then increased in the postpartum.
3. Total serum calcium., ionized calcium, albumin and inorganic phosphorus were all significantly higher in the sera of the newborn infants(venous cord blood) than those of mothers at delivery.
4. Plasma parathyroid hormone levels in the new born infants (venous cord blood) Nvere lower than those o` ?mothers at delivery. In contrast to parathyroid hormone, calcitonin and 25-hydroxy-vitamin D-, levels in ´the new-born infants were markedly higher than those of mothers at delivery.
5. Calcium ti::rnes inorganic phosphorus values declined throughout the pregnancy.
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