Heart Murmurs in Pregnancy: A Phonocardiographic Study of their Development, Progression and Regression

¹ Department of Internal Medicine, Emanuel Hospital, Portland, Oregon
² Chief Resident, Department of Internal Medicine, Emanuel Hospital

Heart murmurs are extremely common in the pregnant patient, occurring in approximately 93 per cent. No specific pattern of distribution by five-week interval could be determined. It was characteristic in 60 per cent of patients that the murmur would appear and disappear at unpredictable intervals. The largest percentage of maximal murmurs is noted in mid-pregnancy (15-25 weeks), showing a gradual but definite decline thereafter to term, with a resurgence in numbers and intensity during active labor and in the immediate postpartum period. This discrepancy of expected correlation of murmur frequency and magnitude with known physiologic circulatory alterations of pregnancy is enigmatic. Possible contributing factors are briefly discussed.

Third heart sounds are also very common, occurring in 83 per cent of patients, in a pattern of distribution similar to that of maximal murmurs.

Patients followed through the six-week postpartum period showed a marked decrease in incidence of heart murmurs.