Amniotic fluid levels of 17 alpha-hydroxyprogesterone during human pregnancy: pre-natal diagnosis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

Levels of 17 alpha-hydroxyprogesterone were estimated by radioimmunoassay in 174 amniotic fluid specimens obtained from 162 normal pregnancies of 16-20 weeks gestation. Another 18 specimens from 11 normal pregnancies between 25-42 weeks gestation and 7 specimens from 7 women who each previously had given birth to a child affected with CAH were also studied. There was no sex difference in AF 17 alpha-OH-progesterone levels, nor any significant downward trend in concentrations throughout the observed gestation period. Among the 7 subjects with previous history of CAH offsprings, 4 demonstrated normal levels of AF 17 alpha-OH-progesterone and 3 significantly higher values. HLA-typing of the cultivated amniotic cells confirmed these 4 cases to be heterozygous for 21-hydroxylase deficiency. The three subjects with high AF 17 alpha-OH-progesterone levels delivered babies affected with CAH, although HLA-typing in one case was non-conclusive. The failure of HLA-typing in 1 case for a confirmatory diagnosis indicates that the prenatal diagnosis of CAH must continue to rest on joint endocrinological and genetical investigations.