Baby Heart Murmur - Innocent vs Concerning
The short answer
Heart murmurs are very common in children - up to 75% of children will have an audible murmur at some point. The vast majority are "innocent" or "functional" murmurs, meaning there is no structural heart problem. These murmurs are simply the sound of blood flowing normally through the heart and are more audible during fever, illness, or excitement. A smaller number of murmurs indicate a structural heart difference that may need monitoring or treatment. Your pediatrician can usually distinguish between the two and will refer for an echocardiogram if there is any concern.
Parents everywhere have the same worry. You are doing the right thing by looking into it.
By Age
What to expect by age
0-1 month
In newborns, the heart is transitioning from fetal circulation to independent circulation. Murmurs heard in the first few days of life may be from normal transitional flow and often resolve. However, some murmurs detected in newborns can indicate congenital heart defects. If your newborn has a murmur along with poor feeding, rapid breathing, bluish skin, or failure to gain weight, evaluation is urgent. Most hospitals now screen newborns with pulse oximetry to detect critical heart defects before discharge.
1-6 months
Murmurs first detected at well-baby visits during this period are common. Many are innocent and related to the rapid blood flow through a small heart. Your pediatrician will listen to the characteristics of the murmur - its timing, location, and quality. A soft, musical murmur in a baby who is feeding well, growing normally, and has no other symptoms is very likely innocent. If there are any questionable features, an echocardiogram is a painless, non-invasive ultrasound of the heart that gives definitive answers.
6-12 months
As your baby grows, the heart grows too, and some murmurs that were audible earlier may become quieter. New murmurs can also appear at this age and are usually innocent. Your pediatrician will continue to monitor the murmur at each well visit. If the murmur has not changed and your baby is thriving, there is usually no need for additional testing. If a murmur is getting louder or your baby is showing any symptoms, further evaluation may be recommended.
12-36 months
Innocent murmurs remain common in toddlers and often become more noticeable during illness or fever because the heart pumps faster. Many parents first learn about their child's murmur during a sick visit. If your pediatrician tells you the murmur sounds innocent and was found incidentally, the reassurance is well-founded. Toddlers with innocent murmurs need no activity restrictions, no medications, and no special precautions. The murmur may persist for years and typically resolves by adolescence.
What Should You Do?
When to take action
- Your pediatrician describes the murmur as "innocent," "functional," or "flow murmur" and your baby is growing and developing normally
- The murmur is soft and musical, only heard in certain positions, and comes and goes
- Your baby has had an echocardiogram that shows a structurally normal heart
- The murmur is more noticeable when your baby has a fever or is excited but absent at other times
- A new murmur is heard that was not present at previous visits
- Your baby seems to tire easily during feeds or becomes sweaty while eating
- You want reassurance about a previously identified innocent murmur
- Your baby has a murmur along with bluish or gray skin color, rapid breathing, poor feeding, or failure to gain weight - these may indicate a significant heart problem
- Your baby is having episodes where they turn blue, especially around the lips and fingernails
- Your baby has a murmur with a rapid or irregular heartbeat that you can feel or see through the chest wall
Sources
Related Resources
Trust your instincts. If something feels wrong, reach out to your pediatrician.
Worrying about your baby means you care. That is a good thing.
Related Medical Concerns
My Baby Is Breathing Fast
Babies normally breathe faster than adults. A normal respiratory rate for a newborn is 30-60 breaths per minute, slowing to 20-40 by age 1. Brief episodes of faster breathing during excitement, crying, or feeding are normal. However, persistently rapid breathing (tachypnea) at rest, especially with other signs of respiratory distress, may indicate a lung or heart problem that needs prompt evaluation.
My Baby Turns Blue (Cyanosis)
Blue or purple discoloration limited to a baby's hands and feet (acrocyanosis) is very common in newborns and usually harmless, caused by immature circulation. However, blue coloring of the lips, tongue, face, or trunk (central cyanosis) is always a medical emergency that requires immediate evaluation, as it may indicate a heart or lung problem.
I'm Worried My Baby Isn't Growing (Failure to Thrive)
Failure to thrive, now often called growth faltering, means a baby is not gaining weight or growing as expected. It is important to know that babies naturally shift percentiles in their first two years, and being on a lower percentile is not the same as failure to thrive. True growth faltering involves crossing two or more major percentile lines downward and usually requires medical evaluation to determine the cause.
My Baby's Head Shape Looks Abnormal
Many babies develop temporary head shape irregularities that are completely normal. A cone-shaped head from vaginal delivery reshapes within days. Mild positional flattening (plagiocephaly) from sleeping on the back is very common and usually improves with repositioning and tummy time. However, head shape changes involving ridges, a persistently bulging fontanelle, or rapid head growth changes should be evaluated to rule out craniosynostosis.
Achondroplasia (Dwarfism) in Babies
Achondroplasia is the most common form of short-limbed dwarfism, affecting about 1 in 15,000 to 40,000 births. It is caused by a mutation in the FGFR3 gene and is usually apparent at birth with characteristic features including short limbs, a larger head, and a prominent forehead. Intelligence is normal. With monitoring for specific complications and supportive care, children with achondroplasia lead full, active, and independent lives.
Adenoid Hypertrophy and Breathing
Adenoids are lymphoid tissue located behind the nose that help fight infection in young children. When adenoids become enlarged (adenoid hypertrophy), they can block the nasal airway, causing chronic mouth breathing, snoring, nasal speech, and sleep-disordered breathing. Enlarged adenoids are most common between ages 2-7 and are a leading cause of obstructive sleep apnea in young children. Treatment ranges from watchful waiting and nasal steroids to surgical removal (adenoidectomy) if breathing or sleep is significantly affected.