decreased fetal derived definitive erythrocyte cell number +
reduced number of fetal liver derived enucleated erythrocytes, which mature in macrophage islands within the liver, enucleate, and then enter the bloodstream; these resemble adult erythrocytes in that they are small (3- to 6- times smaller than primitive erythrocytes) and produce adult hemoglobins
increased fetal derived definitive erythrocyte cell number