Shortness of breath during pregnancy is often caused by which of the following?

• A. Asthma flare due to infection
• B. Anemia from iron deficiency
• C. Hormone-related changes
• D. Lung congestion from infection

Answer: (C)

During pregnancy, the body makes several respiratory adaptations, and a key one is driven by hormones, especially progesterone. Progesterone increases the sensitivity of the breathing center to carbon dioxide, so you breathe more deeply and more often. This rise in minute ventilation lowers CO2 and raises oxygen delivery to both mother and fetus, but it also commonly produces the sensation of shortness of breath, known as physiologic dyspnea, often noticeable as pregnancy progresses.

At the same time, the growing uterus pushes the diaphragm up, reducing some lung volumes. Even though the overall oxygen needs are higher, these hormonal and mechanical changes together commonly explain why shortness of breath occurs in many pregnancies.

Other causes like an asthma flare from infection, iron-deficiency anemia, or lung infection can cause shortness of breath, but they’re not the typical explanation for the common, nonpathologic breathlessness many pregnant people experience.