Pituitary-adrenal and testicular function in preterm infants after prenatal dexamethasone treatment.

Pituitary-adrenal and testicular function was monitored by plasma ACTH and testosterone (T) measurements in preterm newborns (gestational age below 36 weeks), exposed in utero to dexamethasone treatment for prevention of respiratory distress syndrome. A group of age-matched premature newborns and full-term infants served as controls. The cord-blood ACTH level was high in each group (logarithmic means 65-75 ng/l), but decreased within the first 2 days of life to mean levels between 20-30 ng/l on days 3 to 10 inclusive. Dexamethasone treatment had no effect on the postnatal ACTH concentrations when compared with preterm or full-term controls. Similarly, no difference in plasma ACTH were found between untreated preterm and full-term infants during the first 10 days of life. T levels in mixed cord blood were on average 2-3 nmol/l in the preterm male infants. An increase to a mean level of 10 nmol/l was seen in 1 h and 1 d samples. Thereafter, the concentration of T decreased to 2-3 nmol/l on days 3-10 postnatally. No effect of dexamethasone treatment was seen on the postnatal pattern of plasma T. When preterm male and full-term male infants were compared, no difference was seen in the T peak in the first day of life. However, the 1-3, and 60-90 days concentrations of T were 2-fold (p less than 0.01-0.05) higher in the preterm group. It is concluded that prenatal dexamethasone treatment of the mother does not influence the postnatal pituitary-adrenal function as monitored by ACTH measurements. Likewise, no effect of this treatment was observed on the postnatal testicular activity of preterm male infants. The immediate postnatal peak in plasma T levels persisted longer in the preterm than in the full-term male infants.