CLINICAL STUDY Birthsize, gestational age and adrenal function in adult life: studies of dexamethasone suppression and

Objective: Several studies show that low birthweight is associated with long-term alterations in the function of the hypothalamic –pituitary–adrenal axis (HPAA). We recently reported that the relation-ship between birthweight and fasting serum cortisol concentrations differed according to the gesta-tional age of the babies, suggesting that both hypercortisolism and hypocortisolism could be a consequence of impaired fetal growth. We have now extended these findings by examining the relationship between birthweight, gestational age and tests of adrenal suppression and stimulation. Design: Prospective birth cohort study. Subjects and methods: We studied 165 women (mean age 71.3 years) born at term in Helsinki, Finland, between 1924 and 1933, whose body size and gestational age at birth were recorded. These women underwent an overnight 0.25 mg dexamethasone suppression test followed by a 1mg ACTH1 – 24 stimulation test. Results: In all women combined, low birthweight was associated with lower total (P 0.03) and free (P 0.02) cortisol concentrations following dexamethasone. However, these relationships were dependent on gestational age at birth, interactions between the effects of birth size and gestationa