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

During pregnancy, various physiological changes occur in the maternal body to accommodate both the mother and the developing fetus. One of the notable respiratory changes is the increase in arterial oxygen tension, or PaO2, which helps to ensure adequate oxygen delivery to the fetus. This increase is primarily due to a rise in tidal volume as the diaphragm is pushed upward, and greater lung expansion occurs.

As the pregnancy progresses, the demand for oxygen increases to support the metabolic needs of both the mother and the growing fetus. Consequently, the body adapts by improving the efficiency of gas exchange in the lungs, which leads to higher levels of PaO2. This enhancement in oxygenation is crucial, as it supports fetal development and helps to meet the increased metabolic demands during pregnancy.

The other options do not reflect the typical physiological changes that occur during pregnancy. For example, tidal volume actually increases, and inspiratory capacity also tends to increase rather than decrease. Similarly, expiratory reserve volume typically decreases due to the diaphragm being pushed upward by the growing uterus, further supporting the idea that a rise in PaO2 is a key respiratory change in pregnant individuals.