The Effect of Pregnancy on the Murmurs of Mitral and Aortic Regurgitation

The effect of pregnancy on the intensity of murmurs of aortic and mitral regurgitation has not been reported previously. Twenty-five women with these murmurs, singly or in combination, were examined when pregnant as well as when not pregnant. During pregnancy the murmur of aortic regurgitation decreased in intensity or became inaudible in 10 patients, remained unchanged in four, and increased in one. The murmur of mitral regurgitation decreased in intensity or became inaudible in eight patients, became shorter in duration in two, was unchanged in three, and became louder in one. Three of the patients who did not show a decrease in intensity of the mitral or aortic regurgitation murmur and the patient whose murmurs increased during pregnancy had the appearance or persistence of systemic hypertension during pregnancy. Phenylephrine consistently increased the loudness of the murmurs, usually to the level present in the nonpregnant state. The diminished intensity of these murmurs may be related to the decrease in peripheral resistance known to occur during pregnancy. It is apparent that (1) aortic regurgitation or mitral regurgitation may be missed during pregnancy, since these murmurs may become inaudible, and (2) the severity of these cardiac lesions may be underestimated clinically because of a decrease in intensity of these murmurs during pregnancy. It is important to determine the existence of valvular heart disease, since endocarditis is a hazard during parturition, and prophylactic antibiotic therapy should be given to these patients.