Fetal plasma erythropoietin concentration in severe growth retardation

Objective: The aim of this study was to determine whether hypoxemia induces an increase in plasma erythropoietin concentration in human fetal life and, if so, whether this response stimulates fetal erythropoiesis. Study design: The plasma erythropoietin concentration in blood samples from 33 small-for-gestational-age fetuses at 26 to 38 weeks' gestation was measured. Measurements were compared with the reference range for gestation, and associations with Po 2, pH, and erythroblast and erythrocyte counts were examined. Results: The mean plasma erythropoietin concentration in the small-for-gestational-age fetuses was significantly increased, and the degree of increase was significantly associated both with fetal acidemia and, more strongly, with fetal erythroblastosis. Conclusions: Erythropoietin production in response to tissue hypoxia occurs from at least 26 weeks' gestation with measurable physiologic effects on erythropoiesis. Furthermore, more accurate assessment of tissue oxygenation may be obtained by measuring the erythroblast count rather than the blood pH.