Adrenal status during the first month of life in mature and premature human infants.

Measurements of 17-hydroxyprogesterone (17-OHP) in blood collected onto filter paper after heel puncture by lancet and steroid metabolites in random collections of urine, were made in human infants born from 25 weeks of gestation onwards. The concentration of 17-OHP in blood eluted from filter paper samples was inversely related to both gestational age and birth weight. In mature infants, 17-OHP concentrations fell rapidly soon after birth, whereas concentrations remained high over the first month of life in infants born earlier than 33 weeks of gestation. Sulphated urinary steroids were identified as having a 3 beta-hydroxy-5-ene structure and although the pattern of excretion was similar in mature and premature infants, significantly higher concentrations were found in the premature group. Steroid metabolites normally present when concentrations of circulating 17-OHP are increased due to 21-hydroxylase deficiency were not detectable in urine samples collected from infants born prematurely. Where direct comparison of 17-OHP in blood spots and urinary steroid metabolites was possible, the concentrations of 17-OHP in blood samples paralleled 3 beta-hydroxy-5-ene steroid metabolites in urine. The results suggest that a circulating cross-reacting 3 beta-hydroxy-5-ene steroid may be responsible for increased concentrations of 17-OHP in infants born prematurely. Increased concentrations of both 17-OHP in blood spots and steroid sulphates in urine were associated with stress in premature, but not in more mature, infants suggesting that in infants born prematurely postnatal stress may delay adrenal maturation.