A 28-year-old woman who is known to have a cardiac murmur becomes pregnant. It is noted that the intensity of her murmur diminishes during her pregnancy. Which cardiac abnormality is she likely to have?

A. Aortic stenosis
B. Aortic regurgitation
C. Mitral stenosis
D. Pulmonic stenosis
E. Fallot’s tetralogy

The correct answer is B. During pregnancy, cardiac output and blood volume increase from the second month up to the thirtieth week to 30–50% above the normal levels. The average increase in blood volume during pregnancy amounts to 1600 ml, and there is also an increased metabolic workload. This produces warm extremities, a tachycardia with a large-volume pulse and a slight rise in venous pressure. The diastolic blood pressure is lower due to vasodilatation, and this is responsible for the fading of the aortic regurgitation murmur. The apex beat is displaced, because of cardiomegaly and a raised diaphragm. The increased blood flow may produce a pulmonary systolic murmur and a third heart sound. All stenotic murmurs become more prominent.