[The effect of maternal dexamethasone treatment after the 12th week of pregnancy on fetal genital development in adrenogenital syndrome with 21-hydroxylase deficiency].

: Prenatal treatment with dexamethasone starting with gestation week 5 has been proposed to prevent virilization of female fetuses with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. We report dexamethasone treatment in a mother during her third pregnancy; this treatment could not be started before the 12th week of gestation. The second child (index case) had a simple virilizing 21-hydroxylase deficiency CAH and Prader IV genitalia. Because after amniocentesis a normal female karyotype and HLA identity with the index case were found, the dexamethasone treatment (3 x 0.5 mg/die) was continued until delivery.-In contrast to patients with salt-wasting CAH, the 17-alpha-hydroxyprogesterone level in the amniotic fluid was within the normal range. Decreased maternal plasma and urine estriol concentrations, as well as the plasma cortisol values, demonstrated adequate suppression of the fetal and maternal adrenal gland. No side effects were found in the mother as a result of the dexamethasone treatment. The newborn had virilization of the external genitalia according to Prader III but without hypertrophy of the clitoris. The degree of rugated scrotum was less marked in relation to the index case and the sinus urogenitalis was more distally shifted. Thus, surgery on the clitoris could be avoided. The conditions for further surgery (vaginoplasty) could probably be improved. Therefore, dexamethasone treatment of a mother with a female CAH fetus due to 21-hydroxylase deficiency seems to be justified starting at the 12th week of gestation. However, the optimal beginning of therapy is in early pregnancy.