Which of the following statements regarding the respiratory status of a pregnant woman is true?

During pregnancy, a woman's body undergoes several physiological changes to accommodate the growing fetus. One of these changes is related to the thoracic cage, which may indeed appear wider. This widening is primarily due to hormonal influences, particularly the effects of relaxin, which causes the ribcage to expand to allow for increased lung capacity. Additionally, as the uterus enlarges, it can push up on the diaphragm, leading to changes in the shape and size of the thoracic cavity.

The other options do not accurately reflect the typical respiratory changes during pregnancy. For example, the costal angle often becomes wider rather than narrower, and while some women may experience shallow breathing due to the limited space caused by the enlarging uterus, it is generally noted that respiration rate and depth can actually change to accommodate increased oxygen demands. Lastly, oxygenation is typically maintained or sometimes improved during pregnancy due to increased blood volume and cardiac output, which enhances oxygen delivery to both the mother and fetus.

Thus, the statement that the thoracic cage may appear wider is true as it captures a significant and observable change in respiratory status during pregnancy.