Red blood cell survival and kinetics during pregnancy.

Profound changes occur during pregnancy in the maternal hematopoietic system in order to meet the needs of the developing fetus and of the mother. By presenting the available data in one review, this review links all known hematopoietic events that occur during normal and certain abnormal pregnancies. Erythropoietin and erythrocyte production are increased during normal pregnancy while erythrocyte mass per unit of body weight remains constant throughout the entire pregnancy, and hemoglobin and hematocrit continuously decrease into the third trimester. Erythrocyte life span is decreased during normal pregnancy due to 'emergency hemopoiesis' in response to elevated erythropoietin levels. In preeclampsia, maternal erythrocytes are of similar to non-pregnant state age distribution, while fetal erythrocytes are of younger age distribution than in normal pregnancy. In gestational diabetes, maternal erythrocyte age distribution is similar to that of normal pregnancy. In multifetal pregnancy, maternal erythrocyte age distribution is younger than that of normal pregnancy.