The effect of erythropoietin on age distribution of erythrocytes in pregnant mice

Objective: To determine whether experimentally increased levels of erythropoietin in mice could imitate the rightward shift of the density distribution of cell (DDC) curve seen in late pregnancy. Methods: Forty C57BL/6J mice were used. Ten were nonpregnant controls, 10 were pregnant, 10 were nonpregnant mice receiving low-dose erythropoietin treatment, and 10 were nonpregnant mice receiving high-dose erythropoietin treatment. The blood was tested for DDC after 15 days. Results: The cumulative DDC curve of nonpregnant mouse erythrocytes treated with high doses of erythropoietin was shifted to the right as compared with that for mice treated with low doses of erythropoietin and nonpregnant mice. Conclusions: The high erythropoietin levels that are seen in pregnancy may be responsible for the change in the DDC of erythrocytes and, secondarily, a shorter lifespan. We are unable to rule out additional hormonal or physiologic changes that also could affect the hematopoietic system during pregnancy.