Adrenal steroids in maternal and cord blood after dexamethasone administration at midterm.

We undertook a study designed to evaluate whether it is feasible to suppress fetal adrenal secretion of androgens at mid-pregnancy by giving dexamethasone (DX) to the mother. Levels of DX and adrenal steroids were measured in maternal and cord plasma of 13 DX-treated and 16 untreated mothers undergoing abortion at 18-20 weeks of pregnancy. Maternal adrenal suppression was evidenced by a sharp fall of plasma cortisol (F), cortisone (E), corticosterone (B), and dehydroepiandrosterone sulfate (DHEA-S). However, in cord blood no fall of DHEA-S or corticosterone sulfate (BS) was found up to 20 hours after DX administration, and cord plasma ACTH remained detectable. The failure of DX to suppress the fetal adrenal at mid-pregnancy suggests that this drug would not be effective in the intrauterine treatment of congenital adrenal hyperplasia (C.A.H.).