[Fetal and neonatal triiodothyronine (author's transl)]

Thyroid hormones of amniotic fluids give informations about their presence in the fetus. T3 and T4, determined by radioimmunoassay, are found as soon as 12 weeks of gestation. Their amounts are higher at 17 weeks than at 30-40 weeks of gestation. Thyroid tissues of premature and full term neonates were analysed by chromatography after hydrolysis and 127I determined. T3 amount was very low near birth and increased with duration of survival. These results may be related to hormonal serum changes observed in the early neonatal period.