In pregnancy the increased blood supply includes a 45% to 50% increase in plasma volume and 20% to 30% increase in red blood cells. Since these percentages are not equal, the subsequent hemoglobin (HGB)/hematocrit (HCT) will reflect a normal physiologic anemia of pregnancy. The HCT will appear to fall as the volume increases more than the packed cell count. White blood cell (WBC) counts, especially neutrophils, increase naturally during pregnancy.There is also a rise in the number of platelets from 180 x 10^9 to over 300 x 10^9 during pregnancy. Although all women experience some expected changes in clotting, there are defective clotting conditions that greatly affect the outcomes of some pregnancies.
