Plasma Erythropoietin Levels in Cord Blood and in Blood During the First Weeks of Life1

SUMMARY Plasma erythropoietin levels have been studied in cord blood from normal and erythroblastotic infants, and in blood from normal and hypoxic infants during the first weeks of life. The erythropoietins are slightly elevated in cord plasma from normal infants, and markedly elevated in plasma from severely anemic infants. No erythropoietin is detectable in plasma from normal infants during the first weeks of life while hypoxic infants have elevated plasma erythropoietin levels. It is concluded that the vital regulatory mechanism of erythropoiesis through erythropoietins is intact in the last part of intrauterine life and in the neonatal period. The present findings are another confirmation of the concept that the postnatal fall in erythropoiesis is due to an improvement of oxygenation following birth.