What cardiac change occurs in the first trimester?

• A. Increase in ventricular mass
• B. Decrease in stroke volume
• C. No change in heart size
• D. Decrease in heart rate

Answer: (A)

Early pregnancy triggers a rise in circulating blood volume, and the heart adapts to this increased preload by remodeling the left ventricle. This remodeling, known as eccentric hypertrophy, increases ventricular mass to accommodate larger end-diastolic volumes and maintain higher cardiac output. As a result, the heart becomes slightly more muscular in the first trimester. In contrast, heart rate tends to rise rather than fall, and stroke volume increases with the growing blood volume, so a decrease in heart rate or no change in heart size would not fit the expected changes.