What physiological change is typical during pregnancy regarding blood volume and blood pressure?

During pregnancy, the body undergoes significant physiological adaptations to support the developing fetus. One of the most critical changes is the increase in blood volume, which rises significantly to supply the growing placenta and fetus with adequate nutrients and oxygen. This expansion in blood volume is typically around 40-50%, helping to accommodate the needs of both the mother and the baby.

Additionally, blood pressure usually experiences a decrease during the second trimester due to the vasodilatory effects of pregnancy hormones, specifically progesterone. This hormone causes the blood vessels to relax and widen, leading to lower systemic vascular resistance and, consequently, a decline in blood pressure. This phenomenon often helps prevent hypertension during pregnancy, although care must be taken to monitor blood pressure as pregnancy progresses, especially during the third trimester when it may rise again.

Therefore, the choice indicating that blood volume normally increases while blood pressure normally decreases aligns accurately with these physiological changes observed during pregnancy.