What significant change occurs in a mother's blood volume during the second trimester?

During the second trimester of pregnancy, a significant physiological change occurs in a mother’s blood volume, which increases by approximately 50%. This increase is a normal and expected adaptation to support the growing fetus and ensure adequate perfusion to both maternal and fetal tissues.

As pregnancy progresses, especially in the second trimester, the body needs to enhance blood supply to meet the metabolic demands of the developing fetus. The increased blood volume is essential for several reasons, including improved oxygen and nutrient delivery to the placenta and fetus, support for the mother’s expanded circulatory needs, and preparation for potential blood loss during delivery.

The increase in blood volume is accomplished through both plasma expansion and an increase in red blood cell mass, which helps to accommodate the increased blood flow without causing hemodynamic compromise.

The other options do not align with the physiological changes that occur during this stage of pregnancy. A decrease in blood volume is not typical during any stage of pregnancy, and maintaining the same blood volume would not sufficiently support the needs of the mother and fetus. A slight increase by only 10% would also not adequately reflect the significant adaptations required during the second trimester.