Heart defects in newborns are among the most common birth defects in the United States. Heart defects occur during fetal development when the structures of the heart don’t develop normally. Alternatively, heart defects can occur after birth when the newborn heart fails to undergo the normal changes that occur when your baby’s lungs begin to function on their own. Heart defects can range from mild and without symptoms to life-threatening conditions that require immediate medical intervention.

Congenital heart defects (CHD, or congenital heart disease) are sometimes discovered during prenatal ultrasounds but not always. Babies with CHD often appear normal in the first few days after birth and may not have visible symptoms. In the first day or so of life, newborns with CHD may have normal heart sounds when listened to and they may even feed and cry normally.

However, because of the frequency and potentially serious nature of CHD, in 2011 the American Academy of Pediatrics recommended that all newborns should be screened for heart defects. Screening consists of obtaining a pulse-oximetry measurement of the newborn. A pulse-oximeter estimates the level of oxygen in a newborn’s blood by placing a gentle clip-like object on the infant’s toe.

The test is non-invasive, not painful, and can be completed in a matter of seconds. It’s a good test because heart defects frequently result in a lack of oxygen in the blood, so measuring these levels is a good indicator of heart health. Babies with certain types of CHD will have lower than expected pulse-oximetry readings, alerting the newborn nursery staff that something might be wrong

Pulse-oximetry should be done after the first 24 hours of life because readings performed earlier can show up normal even if there is a defect. This is because of special structures in the newborn’s heart that allow blood to mix between the right and left side of the heart. If the pulse-oximetry is too low, the nursery team will decide what additional tests are necessary including a cardiac echocardiogram (ultrasound of the heart).

The specific CHD that newborn screening intends to find include:


  • Screening for critical congenital heart defects is fast, painless, and completed within seconds.
  • While the AAP recommends CHD as part of routine newborn screening, not every hospital in the US routinely screens its newborns.
  • Prenatal ultrasounds can be useful to detect CHD but not every defect will be identified, making newborn screening an important part in the identification of CHD.

Last reviewed by Sara Connolly, MD. Review Date: August 2019


  1. American Academy of Pediatrics. Newborn Screening for Critical Congenital Heart Disease.
  2. Centers for Disease Control and Prevention. Facts about Critical Congenital Heart Defects.
  3. American Academy of Pediatrics. Newborn Screening for CCHD.


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