What to Know About Heart Murmurs in Newborns and Children

Medically Reviewed by Dany Paul Baby, MD on April 08, 2022
5 min read

Your pediatrician listens to your child's heart with a stethoscope to assess its function and health. They hear the first and second heartbeats caused by the valves closing, but they also listen for heart murmurs in newborns and children. 

Your baby may have a newborn heart murmur present at the first examination after birth. Childhood heart murmurs, though, can be a sign of a dangerous disorder. 

There are many types of heart murmurs, and some indicate underlying conditions that necessitate careful assessment.

The heart consists of four chambers. The right atrium and ventricle receive blood from all over the body and pump it to the lungs to be oxygenated. The left atrium and ventricle receive the oxygenated blood and pump it into the aorta to reach every organ and tissue of the body. 

There is a substantial flow of blood through the heart, and most of it moves smoothly and quietly. Four valves in the heart make sure this flow moves in a single direction. 

Audible heartbeats are created by these valves closing. 

Murmurs, in contrast, are sounds produced by:

  • Blood flow through a narrowed valve or reversed flow through a leaky valve
  • Abnormal openings between the heart's chambers
  • Abnormal connections between the major blood vessels coming from the heart
  • Abnormal thickening of heart tissues, resulting in stiff walls
  • Abnormal movement of a valve (for example, mitral valve prolapse with regurgitation)

Not all heart murmurs in newborns and children are dangerous. Two-thirds of children and about three-quarters of newborns have a heart murmur. 

Murmurs are also, however, possible signs of heart disorders.

When your pediatrician hears a childhood heart murmur, they try to assess whether it is a harmless murmur or a sign of a dangerous problem. 

They will take note of the following.

  • The loudness of the murmur
  • The pitch, low or high
  • The location where the murmur is loudest
  • The spread — whether it can be heard over the sides and back of your child or baby's chest
  • The timing of the murmur in relation to the first and second heartbeats

These details enable your pediatrician to decide whether the childhood heart murmur is innocuous or requires further assessment by a pediatric cardiologist

A large proportion of normal newborns and children have harmless murmurs. Most of these murmurs occur in systole, the period when the ventricles are contracting. These murmurs do not spread over a large area of the chest. Their intensity changes as your child changes position. 

Your pediatrician will probably want to investigate these murmurs, though, if:

  • Your child has other abnormalities of the circulatory system
  • Your child has unusual features
  • Your child is not growing well 

Pathological murmurs are often harsh and spread (radiate) all over the chest. They may be heard in diastole (the period when the heart is dilating and filling up), or even continuously. Children with pathological murmurs will often have other signs of illness. 

Murmurs are graded in intensity from Grade 1 to 6. The first four grades can only be heard with a stethoscope, but grades five and six can be felt by putting a hand on the chest over the heart.

Newborn babies often have heart murmurs. However, health defects of the heart (congenital heart diseases) are a concern at this age. Your pediatrician might refer you for further assessment if they're not fully satisfied the murmur is harmful. 

You may be worried about taking your baby with a heart murmur home. Your pediatrician will reexamine your baby after a few weeks, though. If the heart murmur is persisting, they may decide to refer you to a pediatric cardiologist.

Heart murmurs are common, and most are innocent, but a small proportion of heart murmurs are caused by structural or functional disorders of the heart. 

Alert your pediatrician if your child has any of these symptoms.

  • Breathlessness 
  • Frequent chest infections
  • Difficulty breastfeeding or eating
  • Poor growth
  • Sweating while eating
  • A blue tint to the lips and skin (cyanosis)

These signs indicate a pathological murmur, and an associated heart disorder is likely. Your pediatrician will probably advise you to consult a pediatric cardiologist. 

Your child may need to undergo some tests. Echocardiography, for instance, uses sound waves to image the heart, much like an ultrasound. Your pediatric cardiologist can then see the structure and movements of the heart muscles, chambers, and valves. The echocardiogram also detects infected or damaged heart tissue.

An x-ray of the chest can show the size and shape of your baby's heart and the blood vessels in the lungs. This helps diagnose some heart murmurs in newborns and children.

Murmurs may get louder if a child is ill, stressed, or excited. These murmurs usually vanish as the child grows up, but a few may persist into adulthood.

Pathological heart murmurs are caused by an underlying heart disorder. Most often, these are abnormalities present since birth (congenital heart disease). Sometimes, diseases like rheumatic heart disease and infective endocarditis can produce a childhood heart murmur.

Rheumatic heart disease follows a case of streptococcal sore throat. It's the most common heart disease in children and people under 25 years. Your doctor may suspect this disease if your child develops a new heart murmur in late childhood. Apart from heart murmurs, this disease causes joint pains, jerky movements, and skin nodules. 

Rheumatic heart disease can progress to heart failure.

Murmurs are a sign of possible heart disease. Rather than treating the murmur directly, your doctor will want to look for any sign of heart disorder. If your child has a harmless murmur, they will not need any medicines, surgery, restrictions, or frequent tests.

Pathological murmurs, on the other hand, are associated with heart disorders. Treatment depends on the kind of disorder. Some types of congenital heart disease cure themselves over months or years. 

Your pediatrician will advise you to wait and to watch, though, for any signs of progressive disease. Some disorders are initially assessed to be severe or known to be progressive. Such disorders should be treated quickly.

Some heart murmurs are associated with congenital heart diseases that put your child at high risk for heart infections. Such infections, such as infective endocarditis, can damage the valves and other structures of the heart. If your baby's heart murmur is caused by such a disorder, your pediatrician may ask you to give them antibiotics before any dental or surgical procedure.