Net transfer of essential metals from mother to fetus in the second half of pregnancy in the rat.

The blood and plasma as well as fetal, placental and whole conceptus levels of copper, iron, sodium, zinc, potassium, magnesium and calcium were measured in pregnant rats and their fetuses days 11-21 after conception. Maternal blood and plasma concentrations of these metals did not really change in the period studied. In the fetus, the concentrations of iron, zinc and calcium increased, whereas for the other metals, they remained practically unchanged during fetal development. The net cumulative levels of metals in the whole conceptus increased in parallel with fetal growth for most metals, except for the zinc and calcium concentrations which increased at a higher pace, especially after day 16. It is concluded that these data could only be explained by a balanced increase in fetal drainage from the mother, which does not deeply change the homeostatic maintenance of the maternal circulating metal pools.