Change in erythropoiesis with gestational age during pregnancy

To investigate them changes in erythropoiesis during pregnancy, 342 pregnan t and postpartum women were examined for reticulocyte. subpopulations, reti culocyte maturity index (RMI), and serum transferrin receptor (sTfR) levels . The reticulocyte subpopulations were analyzed by flow cytometry, and the sTfR concentration was measured by an immunoenzymometric method. There were no significant differences in the values of reticulocyte subpopulations, R MI, and sTfR between first trimester and non-pregnant women. However, the R MI and sTfR concentration increased gradually from the second trimester of pregnancy, during which time values were twofold higher than those in the f irst trimester, and peaked in the third trimester. Then the RMI and sTfR va lues decreased abruptly 1-4 weeks postpartum and finally dropped to the lev els of non-pregnant women 5 weeks after delivery. The maternal sTfR concent ration correlated significantly with the corrected reticulocyte count (r=0. 52, P<0.01), PMI (r=0.67, P<0.01), and high fluorescence reticulocytes (HFR ) (r = 0.62, P < 0.01); however, the serum ferritin level correlated poorly with the reticulocyte subpopulations during pregnancy. In conclusion, eryt hropoiesis increases with gestational age during pregnancy and returns to n ormal 5 weeks after delivery. Measurement of sTfR in combination with RMI m ay improve the assessment of erythropoietic activity du mg pregnancy.