By what percentage does blood volume increase during pregnancy?

During pregnancy, blood volume increases significantly to support the growing fetus and prepare the mother's body for childbirth. The increase is typically around 30 to 50% compared to the pre-pregnancy levels. This increase in blood volume helps accommodate the increased metabolic demands of both the mother and the developing baby, supports placental circulation, and ensures adequate uteroplacental blood flow.

Additionally, this increased volume helps to protect the mother from the potential loss of blood during delivery, ensuring that there is a sufficient supply to compensate for any hemorrhage. The increase in blood volume is a crucial physiological change that enables a successful pregnancy and healthy outcomes for both the mother and the child.