FAU Advanced Health Assessment Practice Test

The most likely factor responsible for occasional shortness of breath in a third-trimester woman with a normal examination is hormonal changes. During pregnancy, particularly in the third trimester, the body undergoes many physiological adjustments due to hormonal influences. Increased levels of progesterone lead to an enhanced sensitivity to carbon dioxide and result in changes in respiratory patterns, often causing a sensation of breathlessness even when there are no underlying pathological conditions.

Additionally, as the uterus enlarges, it can push against the diaphragm, further contributing to the sensation of shortness of breath. This is commonly referred to as pregnancy-related dyspnea and is a normal occurrence, particularly as the size of the fetus and uterus increases.

While the other factors like asthma, pulmonary embolus, and infection could potentially cause shortness of breath, they would generally present with other associated findings during a physical examination or have a history related to those conditions that are not noted in this scenario. Given that the examination is normal, hormonal changes are the most plausible explanation for the symptom.