Physiologic Murmur of Pregnancy Does NOT Radiate to the Carotids
The physiologic systolic murmur of pregnancy is characteristically a soft grade 1-2 midsystolic murmur best heard at the mid to upper left sternal edge and does NOT radiate to the carotid arteries. 1
Key Distinguishing Features
Normal Pregnancy Murmur Characteristics
- Location: Mid to upper left sternal edge (not aortic area) 1
- Intensity: Soft, grade 1-2/6 1, 2
- Timing: Midsystolic 1
- Radiation: Does NOT radiate to carotids 1
The ACC/AHA guidelines explicitly describe the physiologic pregnancy murmur as localized to the left sternal border without mention of carotid radiation, distinguishing it from pathologic conditions. 1
When Carotid Radiation Indicates Pathology
Carotid radiation of a systolic murmur is a classic finding of severe aortic stenosis, NOT a physiologic pregnancy murmur. 1 The ACC/AHA guidelines specifically state that severe aortic stenosis presents with:
- Loud murmur (grade 4/6 or greater) that radiates to the carotids 1
- Late-peaking systolic murmur 1, 3
- Single or paradoxically split S2 (NOT the physiologically split S2 of normal pregnancy) 1, 3
- Delayed and diminished carotid upstroke 1, 3
Other Normal Continuous Murmurs in Pregnancy
Two additional innocent continuous murmurs can occur in pregnancy but have distinct characteristics:
Cervical Venous Hum
- Location: Right supraclavicular fossa 1
- Character: Continuous with diastolic accentuation 1
- Maneuver: Obliterated by chin movement toward stethoscope or digital jugular vein pressure 1
Mammary Souffle
- Location: Over engorged breast tissue 1
- Timing: Late pregnancy or early puerperium 1
- Character: Systolic or continuous 1
- Maneuver: Obliterated by firm stethoscope pressure; disappears when standing 1
Clinical Implications
Red Flags Requiring Echocardiography
If a systolic murmur DOES radiate to the carotids in pregnancy, this warrants immediate echocardiographic evaluation as it suggests:
- Aortic stenosis (potentially severe) 1, 2
- Grade 3 or louder murmur intensity 2
- Any diastolic component 1, 2
- Symptoms (dyspnea beyond normal pregnancy, chest pain, syncope) 4, 2
Why This Distinction Matters
The increased blood volume (50% increase) and cardiac output of pregnancy can accentuate murmurs of stenotic lesions like aortic stenosis. 1 Severe aortic stenosis carries high maternal and fetal risk during pregnancy due to the fixed cardiac output state being unable to meet increased hemodynamic demands. 1, 4
Common Pitfall
Do not dismiss carotid radiation as "just a pregnancy murmur." A normally split S2 reliably excludes severe aortic stenosis 1, 3, but if the murmur radiates to the carotids with other concerning features (loud intensity, abnormal S2, symptoms), this represents pathology requiring urgent evaluation regardless of pregnancy status. 1, 2