Amniotic fluid steroid levels and fetal adrenal weight in congenital adrenal hyperplasia.

The concentration of 17-OH-progesterone was determined in second trimester amniotic fluid collected from 58 pregnancies at risk for fetal 21-hydroxylase deficiency. The prediction was incorrect in 1 male nonsalt-loser who had an increased plasma 17-OH-progesterone concentration at 3 months of age. All 11 infants predicted to be affected were salt-losers. The adrenals from 2 affected fetuses available for study were significantly enlarged in comparison with adrenal size in 84 normal fetuses from 15 to 26 weeks' gestation. Amniotic fluid steroid analysis reliably predicts the fetus with 21-hydroxylase deficiency most at risk in early infancy. There is no evidence from this study to indicate that ACTH is not the main trophic factor for fetal adrenal growth and steroidogenesis.