Erythrocyte pressure product is the ratio of the volume of whole blood occupied by sinking red blood cells after a certain amount of blood has been anticoagulated, also called erythrocyte specific volume or erythrocyte specific volume. The measurement of erythrocyte pressure product can indirectly reflect the number, size and volume of red blood cells. A decrease in erythrocyte pressure product usually means a decrease in red blood cells, and once there is a decrease in red blood cells, various kinds of anemia may occur. However, in practice, the measurement of erythropoietic pressure volume is greatly influenced by the volume of red blood cells and plasma volume, and therefore erythropoietic pressure volume does not accurately reflect red blood cell values. In clinical practice, a simple decrease in erythropoietic pressure can not fully confirm the diagnosis of anemia, and a combination of red blood cell count and hemoglobin concentration is needed to make the diagnosis. In addition, physiological causes such as excessive water consumption and pregnancy can also lead to blood thinning, resulting in a relatively low erythropoietic blood pressure. Therefore, if a pregnant woman only has a low RBCP but other indicators are normal, it is not clinically significant and regular review is sufficient.