Prenatal treatment of congenital adrenal hyperplasia: report of a new case.

A mother at risk for 21-hydroxylase deficiency was treated with oral dexamethasone (0.5 mg 12 hourly) from early pregnancy, in an attempt to prevent in utero virilization in case of a female fetus. Fetal karyotype was 46,XX, and because of a possible intra HLA recombination, treatment was continued to term. The newborn had a modest virilization and hormonal studies confirmed the diagnosis of congenital adrenal hyperplasia (CAH). This observation and review of the literature suggest that efficient prenatal treatment of CAH requires a higher and more frequent dosage of dexamethasone.