What changes in blood volume occur during pregnancy?

During pregnancy, there is a significant physiological adaptation in a woman's body to support the needs of the developing fetus. One of the most critical changes is the increase in blood volume, which typically rises by approximately 40-50%. This increase is essential for several reasons: it helps meet the increased metabolic demands of both the mother and the fetus, ensures adequate nutrient and oxygen delivery, and provides a reserve to compensate for blood loss that may occur during childbirth.

The increase in blood volume is largely due to the expansion of plasma volume and red blood cell mass, which helps to enhance circulation and maintain blood pressure despite the added volume. This adaptation is vital to support fetal growth and development throughout the pregnancy. Consequently, the choice indicating a 40-50% increase accurately reflects this physiological change and its significance in pregnancy management.