Origin of corticosteroids in amniotic fluid.

Abstract

The rise in amniotic fluid (AF) corticosteroids which occurs towards the end of pregnancy has been shown to correlate with fetal lung maturity. To elucidate the origin ofcorticosteroids in AF, we measured the concentrations of cortisol (F), cortisone (E), F sulfate (SF), E sulfate (SE), and corticosterone sulfate (SB) in samples obtained simultaneously from maternal peripheral vein (MPV), umbilical artery (UA), umbilical vein (UV), AF, newborn urine (Ur), and fetal pulmonary fluid (PF). The mean concentrations of SF, SE, and SB in AF were significantly (P < 0.05) lower than those in Ur (6- to 8-fold) or those in PF and significantly higher than those in MPV (SF and SB) or those in UA and UV (SF), indicating that fetal urine and PF are the major sources of SF, SE, and SB in AF. The mean concentration of unconjugated cortisol in AF was 26-fold lower than that in MPV and slightly lower than that in PF (P < 0.05) but not different from that in Ur, UA, or UV. The mean concentration of unconjugated cortisone in...