Post-natal development of protein C in full-term newborns.

The purpose of this study was to determine the concentration of Protein C in the blood of full-term healthy newborns. The levels of Protein C, evaluated by electroimmunoassay, were low in the first 5 days of life and lower than the critical adult thrombotic level. The antigenic activity increased progressively from the 2nd week of life and the adult values were reached after the 6th month. The reduction of Protein C levels may impair the ability of the newborn to control consumptive disorders, thus exposing the infants to the risk of thrombotic conditions in neonatal age.