What physiological changes occur in the cardiovascular system during pregnancy?

During pregnancy, significant adaptations occur in the cardiovascular system to support the growing fetus and meet the increased metabolic demands of the mother. One of the key changes is the increase in blood volume, which can rise by 30-50% to ensure adequate blood flow to the placenta and to meet the needs of both the mother and the developing baby.

Alongside the increase in blood volume, cardiac output also rises. This is primarily due to an increase in stroke volume, which is the amount of blood pumped by the heart with each beat, as the heart's workload increases to accommodate the higher blood volume being circulated.

Additionally, systemic vascular resistance decreases during pregnancy. This is a result of the hormonal changes that promote vasodilation, allowing blood vessels to expand and reduce resistance to blood flow. This decrease in resistance, combined with increased blood volume and cardiac output, helps maintain adequate perfusion to the uteroplacental system.

The changes that are listed in the correct answer accurately reflect these physiological adjustments, highlighting the increased blood volume, increased cardiac output, and decreased systemic vascular resistance that are characteristic of a healthy pregnancy.