[Distribution of glucocorticosteroids between free and bound fractions in maternal, fetal, and neonatal plasma in rats, during the perinatal period].

In delivering rats on day 21 of pregnancy, in the afternoon, the free plasma corticosterone concentration is not statistically different from the value found in pregnant females which have not yet delivered at the same stage of pregnancy in the afternoon; moreover there seems to be an equilibrium between maternal and foetal concentrations. In the just expelled newborns, the free plasma corticosterone concentration is much higher than the value found in the littermate foetuses remaining in utero.