The normal course of pregnancy, as noted earlier, is accompanied by an increase in BCC. This increase is due to both the volume of the plasma and the volume of the formed elements of the blood.
The number of circulating red blood cells progressively increases throughout pregnancy. This is due to the stimulating effect of erythropoietin, which is synthesized by the kidney tissues under the action of progesterone. Increased hemopoiesis and an increase in the absolute number of red blood cells are accompanied by an increase in the total oxygen capacity of the blood and are aimed at compensating for the increased body's need for oxygen by accelerating its transfer through the bloodstream.
However, the function of the hemopoietic organs lags behind the rate of increase in the volume of the circulating fluid, therefore autoimmodilation takes place during pregnancy, which is accompanied by a decrease in the hemoglobin level and the number of red blood cells per unit volume of blood. This is a significant factor contributing to the occurrence of anemia.
The number of white blood cells during pregnancy fluctuates in a wide range (from 5х109 /l to 12х109 /l). On average, it slightly increases due to the increase in the level of neutrophils.
The amount of platelets during pregnancy does not change significantly.
Since the early pregnancy (12 weeks gestation process), there is a tendency to increase blood clotting activity. The blood content of fibrinogen increases, and in the last 2 months of pregnancy the increase in this protein in the blood is more intense. Since the 6th month of gestation, other shifts in the blood clotting system have appeared: the time of recalcification is shortened, the plasma tolerance to heparin increases, the retraction rate and clot formation increase. Fibrinolytic activity decreases, especially before delivery.
Such shifts in the balance between coagulation and protizissidalimy properties of blood in the direction of hypercoagulation is an important adaptation (the process of blood loss in childbirth).