[Radio-in-vitro studies of the thyroid status of mature newborn infants immediately post partum].

145 cord sera from fullterm, vital eutrophic newborn babies of uncomplicated pregnancies have been tested for the thyroid gland parameters RT3-U, ST3-U, T4, T3, T4/T3-ratio, total balance of free iodine-hormone indices and TSH to answer the questions of the thyroid gland situation. In the fullterm newborn baby an euthyroid metabolic balance was found on comparison with the simultaneously determined thyroid specific situation of the adult. The T3-situation is identical with that of the euthyroid adult. Thyroid levels, the conversion of T4 to T3 as well as the values of the total balance are slightly elevated, like in women under contraceptive hormone therapy. The basal TSH secretion immediately post partum is similar to the one on day 5 post partum.