Which of the following is a respiratory change that decreases during pregnancy?

During pregnancy, several physiological changes occur in the respiratory system to accommodate the needs of the developing fetus. One significant change is in the functional residual capacity (FRC), which decreases. FRC is the volume of air that remains in the lungs after a normal expiration. As the uterus expands, it pushes up against the diaphragm, limiting lung expansion and decreasing the volume of air that can be retained in the lungs after exhalation.

In contrast, other measures such as tidal volume, inspiratory capacity, and vital capacity generally increase or remain stable during pregnancy. Tidal volume, which is the amount of air inhaled or exhaled during normal breathing, typically increases due to hormonal changes and increased metabolic demands. Inspiratory capacity, the maximum volume of air that can be inhaled after a normal expiration, and vital capacity, the total amount of air that can be exhaled after taking the deepest breath possible, also show similar trends.

This decrease in functional residual capacity is particularly relevant in the context of maternal health, as it can influence a pregnant woman's respiratory reserve and response to physical activity. Understanding these changes is crucial for managing respiratory health during pregnancy.