What is a common cardiovascular change observed during pregnancy?

During pregnancy, there are significant physiological changes that occur to support the developing fetus and accommodate the increased demands on the mother's body. One of the key changes is the increase in blood volume. This expansion in blood volume, which can increase by 30-50%, is crucial for several reasons.

Firstly, it helps to ensure that there is adequate blood flow to the placenta, which is vital for delivering oxygen and nutrients to the growing baby. Secondly, the increase in blood volume assists in preparing the mother's body for the blood loss that can occur during delivery. It also aids in maintaining blood pressure and organ perfusion during the pregnancy when the body is undergoing many adjustments.

In contrast, some other options reflect changes that do not align with the physiological adaptations of pregnancy. For instance, cardiac output actually increases during pregnancy to meet the heightened metabolic demands, while resting heart rate typically increases as well, rather than decreasing. Oxygen demand also rises, as the body's metabolic rate increases to provide for both mother and fetus. Thus, the increase in blood volume is a fundamental cardiovascular change that underscores the body's remarkable ability to adapt to the demands of pregnancy.