Heart murmurs in newborns are heard in about 0.5–1% of babies during routine checks, and many are harmless transition sounds.
Hearing the phrase “heart murmur” right after birth can rattle any parent. In newborns, a murmur is a sound made by blood moving through the heart or vessels. Many murmurs in the first days come from normal changes as a baby switches from womb to world. Some point to a heart defect that needs timely attention. Knowing how common newborn murmurs are, which signs matter, and how doctors sort them out helps you stay calm for parents and caregivers at home.
How Common Are Heart Murmurs In Newborn Babies: Real-World Numbers
On routine nursery exams, an audible newborn murmur shows up in a small slice of babies. Large studies report rates around half to one percent in the first days of life. A classic neonatal study found murmurs in less than one percent at routine checks, while broader pediatric reviews describe a wider range when different methods or ages are included. In short, most newborns will not have a murmur heard before discharge, and when one is found, teams follow clear steps to sort harmless from serious.
Screening does not rely on ears alone. Hospitals now pair the exam with pulse oximetry to pick up critical heart defects that may not cause a loud sound. That safety net catches many babies who need fast care, even when a murmur is faint or absent. You can read the current algorithm on the CDC pulse oximetry screening page. A helpful AAFP review explains evaluation and referral patterns.
| Measure | Typical Rate | Source Snapshot |
|---|---|---|
| Newborns with a murmur at routine exam | ~0.5–1% | Neonatal studies and UK hospital guidelines |
| Any murmur in infants without syndromic signs | ~0.6–8.6% | Family practice review of infant murmurs |
| With a murmur who have a structural defect | ~37–50%+ | Neonatal series using echocardiography |
| Congenital heart disease in all births | ~0.8–1% | Standard epidemiology texts |
| Share of heart defects that are critical | ~25% of CHD | Public health screening guidance |
These figures sit within the range seen across nursery programs.
Why Prevalence Numbers Seem To Differ
Reports vary because studies use different time windows, settings, and definitions. Some include only day-one term babies; others track the first weeks or all infants. Examiner skill and how quiet the room is also matter. Narrow studies report lower rates; broader reviews report higher ones.
The mix of diagnoses also shifts by study. A nursery that scans every murmur will find small ventricular septal defects that would have closed on their own. A center that scans only when red flags appear will count a smaller set, skewed toward more serious lesions. Both approaches aim for safe care; they draw the line at different points based on local resources and pathways.
For parents, the takeaway is simple. A murmur in a brand-new baby is not the same thing as a murmur in a school-age child. Newborn murmurs deserve a careful look because the chance of a structural cause is higher at this age than later in childhood, even though many are still benign.
Why A Murmur Can Be Normal In The First Days
Right after delivery, the heart and lungs switch plumbing. That change can make temporary sounds as blood flow patterns settle. Clinicians often hear two benign newborn murmur patterns.
Patent Ductus Arteriosus Sounds
Before birth, a short vessel called the ductus arteriosus lets blood bypass the lungs. After birth it narrows and closes. While that happens, a soft “whoosh” can be heard near the left upper chest. In many term babies this fades within the first day or two.
What Parents Notice
Usually nothing beyond a soft sound heard by the clinician; feeding and color stay normal.
Peripheral Pulmonary Stenosis Sounds
Newborn branch lung arteries are small and flexible. As they widen, gentle turbulence can create a soft murmur that radiates to the back or underarm. This pattern often fades over weeks to months and the baby feeds and grows well.
Typical Timeline
The sound often fades by three to six months as branch arteries widen.
When A Murmur Signals Heart Disease
Murmurs are sounds, not diagnoses. In some newborns the sound reflects a structural heart problem such as a septal defect, valve issue, or an outflow obstruction. Studies show that a sizable share of neonates with an audible murmur have a lesion on echocardiogram. A small fraction have a critical defect that needs surgery or catheter treatment in the first year. That is why careful checks, oxygen saturation screening, and timely referrals are standard.
What A Clinician Listens For
The timing, location, and quality of the sound guide decisions. Systolic versus diastolic timing, radiation to the back, a click, or a harsh quality can all hint at a structural cause. The rest of the exam matters just as much: breathing pattern, pulses in the legs, liver size, and oxygen levels. A quiet baby resting skin-to-skin often gives the clearest clues.
Risk Factors That Raise Suspicion
- Family history of congenital heart disease or sudden cardiac death
- Maternal diabetes, lupus, or certain medication exposures during pregnancy
- Chromosomal conditions or extra findings on the newborn exam
- Preterm birth or low birth weight
Red Flags You Should Not Ignore
- Blue or gray lips or tongue, or breathing that seems hard even at rest
- Poor feeding, heavy sweating with feeds, or low energy
- Fast breathing, pauses in breathing, or grunting sounds
- Cool legs or weak femoral pulses
- Oxygen saturation below nursery targets or a big gap between hand and foot readings
- A murmur that is loud, harsh, or grows stronger over time
Screening And Diagnosis In The Nursery
Every baby gets a head-to-toe exam that includes listening over multiple spots on the chest and back. Pulse oximetry adds a quick check for low oxygen levels. A low reading, a large pre- and post-ductal gap, or concerning signs prompt more tests. The next steps can include an echocardiogram, chest X-ray, and lab checks. Some nurseries can scan on site; others arrange a fast cardiology review.
Pulse oximetry screening has become standard across the United States and many other regions. The test uses a small sensor on a hand and foot and takes a few minutes while the baby rests or feeds. A pass on pulse oximetry does not rule out every heart problem, yet it lowers the chance that a critical defect slips through.
| Test | What It Checks | What Results Mean |
|---|---|---|
| Pulse oximetry | Oxygen saturation in right hand and either foot | Low or mismatched readings trigger repeat checks or cardiology work-up |
| Echocardiogram | Heart structure and blood flow | Shows holes, valve issues, ductus flow, or outflow blockage |
| Chest X-ray | Heart size and lung markings | Helps interpret findings when a murmur is present |
Taking Care After Discharge
Many families head home with a documented soft murmur and a plan to recheck. Nurses teach parents how to spot breathing trouble, poor feeding, or color change. A follow-up visit confirms that the sound has faded or guides a referral if the sound persists. Babies with an innocent pattern usually eat well, gain weight, and look pink and comfortable.
Treatment Paths When A Defect Is Found
Care depends on the diagnosis. Small holes in the heart wall often close on their own and need only watchful follow-up. Some valve issues improve as the baby grows. Duct-dependent lesions need medicine to keep the ductus open until a surgical or catheter plan is ready. Centers with pediatric cardiology guide timing and steps so newborns stay stable and safe.
How Your Care Team Decides On Referral
Decisions blend the exam, oxygen readings, family history, and how the baby looks during feeds and sleep. Newborn murmurs carry a higher chance of finding a structural issue than murmurs in older children, so many nurseries involve pediatric cardiology early. That approach balances speed and safety without sending every baby straight to scans.
How To Support A Baby With A Murmur At Home
Feed on demand and give the baby time to rest if breathing seems fast during a bottle or at the breast. Keep visits for scheduled weight checks. If lips look blue, if the baby sweats a lot with feeds, or if breathing looks hard, seek same-day care. Trust your instincts and ask questions; teams would rather see a well baby than miss a change.
Questions To Ask Before Going Home
- What did the oxygen readings show, and were both the hand and foot checked?
- Where was the murmur loudest, and what pattern did it have?
- Do we need an echocardiogram now, or is a clinic visit already booked?
- Which warning signs should lead us to the emergency department tonight?
- When is the first follow-up, and who will listen again?
What Parents Should Remember
Newborn heart murmurs are not rare language in a nursery note, yet they are uncommon across all babies. Rates cluster around one percent on routine checks, and many are short-lived sounds from normal circulation shifts. A portion point to a heart defect, and a small share of those are critical. Universal pulse oximetry, careful exams, and clear follow-up protect babies while avoiding panic. With that system in place, most families move from worry to relief over the first weeks safely.