1. and Howard Cord blood was obtained after delivery and ligation of the umbilical cord by withdrawing with a syringe 3 to 5 ml venous blood from the placental side. This was stored and taken at 40C to a central laboratory. After being separated by centrifugation, sera were stored at -200C until analysis. All assays were performed in duplicate. Using 25 pd serum samples, cord T4 was measured in all infants by a double antibody radioimmunoassay (RIA) technique;Walfish, Ginsberg; Rosenberg;et al; Walfish,1972