Common Newborn Screening Tests: Identify Health Conditions Early

Newborn screening tests are an important tool to help identify conditions that may not be apparent after birth. If these conditions are not identified early, lifelong health consequences, severe illness, and premature death can occur.

Key takeaways:
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    Newborn screening tests help to identify health conditions that have lifelong effects, and some can even be fatal.
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    Each state has different newborn screening requirements, but all states perform a simple blood test called Phenylketonuria (PKU).
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    The most common newborn screening tests include Phenylketonuria (PKU), heart screening, and hearing screening.

Each state determines which newborn screening tests are required after delivery. Newborn screening can be overwhelming for new parents, but it is vital testing required for the future health and well-being of your baby.

Why do babies require testing after birth?

According to the Centers for Disease Control and Prevention (CDC), over 13,000 babies in the U.S. are diagnosed with serious health conditions like blood disorders, congenital heart defects, and metabolic disorders. Newborn screening also identifies babies with hearing loss.

Some of the conditions tested during newborn screening are life-threatening, and early diagnosis and intervention help prevent developmental delay, disability, and premature death. Many of the conditions do not become apparent until long after birth but can be identified early on through newborn screening.

Which tests will be performed?

Every state determines which testing is required after birth, and many states will follow the national guideline for newborn screening, the Recommended Uniform Screening Panel (RUSP). Phenylketonuria (PKU) is required by all states, and the majority of states also test for heart defects and hearing loss.

Before your baby is born, you can verify which tests the hospital in your state will be required to complete. The common tests performed during newborn screening may include:

Phenylketonuria (PKU)

PKU testing identifies a rare inherited condition in which the body is not able to properly break down the essential amino acid phenylalanine, which is naturally found in the proteins of many different foods. Breast milk also contains phenylalanine. When the body cannot effectively process phenylalanine, it can build up in the bloodstream and brain.

PKU is a simple blood test that is performed by pricking the heel of the baby’s foot with a small needle and placing drops of blood onto a newborn screening card. This paper card is then sent off to a laboratory to test for PKU and numerous other conditions.

PKU testing is critical because the buildup of phenylalanine can cause the following:

  • Brain damage.
  • Developmental delay.
  • Behavior and mood changes.
  • Neurological problems.
  • Microcephaly (unusually small head).
  • Alteration in skin pigmentation.
  • Skin conditions like eczema.

Heart screening

Critical congenital heart defects (CCHD) can be detected by placing a pulse oximetry sensor on the baby’s right hand or foot to measure the levels of oxygen circulating in the blood. Babies with CCHD may have difficulty breathing, appear blue or pale, and be overly sleepy. Some of the different types of CCHDs that are detected on newborn screening include:

  • Transposition of the great arteries.
  • Hypoplastic left heart syndrome.
  • Tetralogy of Fallot.
  • Truncus arteriosus.
  • Tricuspid atresia.

If a baby does not pass the pulse oximetry test, further testing will be ordered and may include an echocardiogram (ultrasound of the heart), chest x-ray, or electrocardiogram (ECG/EKG), which examines the electrical activity of the heart. A consultation with a pediatric cardiologist may also be necessary.

Hearing screening

Screening for hearing loss is a simple test that can be quickly performed, usually while the baby is sleeping. A newborn hearing screen technician will perform the test before the baby is discharged home. The test measures how the ear responds to sounds and/or how the brain responds to sounds. These tests are called Otoacoustic Emissions (OAE) and Automated Auditory Brainstem Response (AABR).

Not all babies who fail the newborn hearing screen have hearing loss. Sometimes the test simply needs to be repeated. If hearing loss is suspected, the baby will need to be examined by an audiologist, a doctor who specializes in hearing.

What happens if a test has abnormal results?

If the PKU test results are positive, the test will be repeated to verify the results. If a baby does have PKU, she or he will need to be placed on a special low-protein diet. Follow your pediatrician’s recommendations.

When a baby fails the pulse oximetry screening, further cardiac tests will be ordered to determine if there is a heart defect present. A pediatric cardiologist will diagnose the type of defect the baby has and what the best treatment option is.

Failing a hearing screen does not always mean the baby has hearing loss. The test will be repeated, and if necessary, an audiologist will examine the baby to ultimately determine if there are any hearing problems present. Babies with hearing loss may need hearing aids or a cochlear implant.


Newborn screening is an important set of tests that help to identify conditions in newborns that may otherwise not be apparent right after birth. Some of the conditions are life-threatening. Each state determines which tests are required after delivery. If a baby has abnormal test results, further testing and assessment will be performed.


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