We carried out studies to determine the relationship between the production of maternal steroid and function of the fetal adrenal gland and placenta during pregnancy.
The blood CBG levels in normal pregnant women increased gradually with increase in the number of weeks of gestation and reached a peak or 2 to 3 times that of early pregnancy at 39 to 40 weeks' gestation.
In pregnant women with anencephalus and intrauterine fetal death where the maternal estrogen decrease markedly, the maternal blood CBG showed a level lower than the normal range in normal pregnant women.
In pregnant women with hepatic lesion, it was confirmed that maternal blood 11-OHCS and CBG levels were lower than the normal range in normal pregnant women.
Thus, an overall increase in blood CDS in pregnant women is due not to an increase in free cortisol but rather to an increase in cortisol bound to CBG.
It is considered that CBG is synthesized and metabolized in the maternal liver and that estrogen acts in such way as to promote CBG synthesis in the liver.
The cortisol bound to CBG is probably pooled in the maternal blood and compensates for loss of the hormone in cases where the maternal hormonal secretion has decreased sharply by one reason or another.