Rarity of congenital adrenal hyperplasia in children born very preterm:Possible mechanism and implication for newborn screening.

Introduction: Screening for congenital adrenal hyperplasia through the measurement of 17-hydroxyprogesterone on the neonatal blood spot aims to: a) prevent neonatal deaths; b) allow earlier identification and thereby decrease the severity of the initial salt-wasting episode; and c) shorten the time during which a severely virilized genetic female newborn may be assigned the male sex. It is now practiced in the majority of high-income countries, although the positive predictive value of the test is very low in infants born preterm, who seem to be infrequently affected. In almost all low- and middle-income countries, it has not yet been implemented.