Concentrations of aldosterone, corticosterone, 11-deoxycorticosterone, progesterone, 17-hydroxyprogesterone, 11-deoxycortisol, cortisol, and cortisone determined simultaneously in human amniotic fluid throughout gestation.

Corticosteroids (CS) are essential for fetal organ maturation; yet, knowledge of endogeneous CS and precursor levels throughout fetal life is limited. Therefore, unconjugated aldosterone (Aldo), corticosterone (B), 11-deoxycorticosterone (DOC), progesterone (P), 17 alpha-hydroxyprogesterone (17-OHP), 11-deoxycortisol (S), cortisol (F), and cortisone (E) were simultaneously determined by RIA after automated Sephadex LH-20 chromatography in 70 control samples of amniotic fluid (AF) obtained at all gestational ages between 14-42 weeks. Levels of the progestins P and 17-OHP slowly increased from means (+/- SE) of 14.7 +/- 2.8 and 1.63 +/- 0.21 ng/ml, respectively, in early gestation to maximum levels of 32.4 +/- 3.5 and 3.80 +/- 0.74 ng/ml at 36-38 weeks (P less than 0.005), then dropped significantly (P less than 0.01) to 19.2 +/- 2.2 and 1.58 +/- 0.22 ng/ml at term. All CS levels except E rose very markedly by 3- to 12-fold (P less than 0.0001) from the weeks 14-16 (DOC, 0.44 +/- 0.08; B, 1.49 +/- 0.23; Aldo, 0.043 +/- 0.012; S, 0.51 +/- 0.10; F, 5.96 +/- 0.93 ng/ml) until the 36-38th weeks (DOC, 3.50 +/- 0.66; B, 4.60 +/- 0.78; Aldo, 0.530 +/- 0.109; S, 6.00 +/- 0.75; F, 60.8 +/- 8.9 ng/ml). Term levels were significantly reduced (P less than 0.01) in the less active CS DOC (0.51 +/- 0.07 ng/ml), B (2.35 +/- 0.35 ng/ml), and S (1.14 +/- 0.14 ng/ml), whereas those of the biologically most potent CS Aldo and F declined less markedly (0.272 +/- 0.053 and 23.0 +/- 0.75 ng/ml, respectively, at 39-42 weeks). Levels of the inactive glucocorticoid E rose from 8.83 +/- 1.08 ng/ml at 14-16 weeks to 16.8 +/- 2.6 ng/ml at 31-35 weeks (P less than 0.01), then remained rather constant around 11.5 ng/ml until term. It is concluded that after the 25th week, large amounts of biologically active CS are available in AF which probably directly induce the final epithelial maturation of fetal lungs and intestinal tract.