Abstract
Simultaneous determination of unconjugated16α-thydroxypregnenolone (16αOHPreg), 16α-hydroxyprogesterone (16αOH-Prog) and16α-hydroxydehydroepiandrosterone (16αOH-DHEA) in fetal and neonatal plasma was performed utilizing a newly developed radioimmunoassay. In all neonates, the three16α-hydroxysteroid levels were consistently higher in umbilical cord plasma than in the maternal peripheral circulation. 16αOH-Preg in the umbilical arterial plasma increased from11.2±3.1 at24weeks to29.7±12.0ng/ml at term, 16αOH-Prog from15.5±3.2to34.3±11.0 ng/ml and16±OH-DHEA from5.1±1.2to5.9±1.0ng/ml. In the anencephalic neonates, only 16αOH-Preg showed an increase pattern under ACTH priming. 16α-OH-Preg levels for normal full term neonates remain relatively constant at the first 24hr and show a slight decrease at3days post partum. In small full term neonates, 16αOH-Preg levels in umbilical arterial plasma are considerably higher than in normal neonates and remain at roughly equivalent levels for the first5days post partum. 16αOH-Prog and 16αOH-DHEA levels in umbilical arterial plasma in normal and small full term neonates are almost equal and both groups show a rapid decrease during the first24hr. Comparison with findings of the three16α-hydroxysteroids in fetal and neonatal plasma is discussed.
