CBC (complete blood count) Gestational age should be taken into account when assessing hemoglobin, as levels decrease during pregnancy due to haemodilution caused by increased plasma volume. The lower limit for hemoglobin is usually 115 g/L, but for pregnant women, the lower limit is usually reported as 100 g/L. Higher than normal white cell counts and platelet counts are common during pregnancy, but their significance depends on the gestational age of the fetus. Hematocrit levels generally increase during early pregnancy because of increased red cell mass due to erythropoietin production by the developing fetus. However, hematocrit levels may also appear low in early pregnancy when compared with later stages because of the effect of fetal erythropoiesis on maternal red cells. In late pregnancy, blood volume increases due to fluid retention by the uterus so that overall hemoglobin concentration remains constant. Therefore, an individual with high baseline hemoglobin levels will have higher values at later stages of pregnancy. Erythrocyte indices may vary depending on the method used for analysis. Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) are all affected by changes in red cell size and hemoglobin content. While all these parameters tend to increase during early pregnancy, MCV and MCH decrease toward the end of pregnancy when more large and young red cells are produced.