During pregnancy, how does blood volume change?

During pregnancy, blood volume undergoes significant changes to support the developing fetus and adapt to the physiological demands of the mother. Specifically, blood volume increases by 30-50% by the end of pregnancy. This increase is primarily due to the body's need to supply adequate nutrients and oxygen to the placenta and fetus, as well as to prepare for the blood loss that might occur during delivery.

The increase in blood volume also helps to improve uteroplacental circulation and enhances the mother's cardiovascular system, accommodating the increased fluid needs for both maternal tissues and fetal growth. This expansion of blood volume is mostly made up of plasma volume, which increases at a greater rate than red blood cell production, often leading to a relative dilution of hemoglobin.

Understanding this physiological change is crucial as it can influence various aspects of prenatal care, maternal health, and the management of potential complications during pregnancy.