What to Know About Newborn Screening Tests

Medically Reviewed by Renee A. Alli, MD on June 15, 2024
4 min read

Newborn screening tests are a service of the public health department performed daily in each US state. Each newborn is tested for a number of health disorders that are not supposed to be present at birth. Early detection can be critical to survival.

Newborn screenings help you to quickly discover serious and rare birth conditions. Most newborn screening tests yield normal results, but if not, your baby will get a more personalized diagnostic test. When a medical condition is found early, it can often be treated. Early treatment is vital because it could prevent future health issues for your baby.

In the U.S., all babies receive a newborn screening. Annually, about 4 million babies are tested. With a simple blood test, your doctor can test for hormonal, genetic, and metabolic conditions that can, if untreated, lead to serious health problems. Newborn screening allows doctors to quickly assess babies and began treatment ASAP if needed.

When the baby is a day or so old, the special screening is performed. It includes hearing, heart, and blood testing. A heel prick is used to get a sample of your baby's blood. The drops are collected on a special paper or in a small vial. It is then sent off for testing.  The heel could have a little redness at the prick site, and maybe a little bruising, but the irritation goes away in a few days. 

Specific screening tests differ by state and region. The different tests offered by the state change as technology changes and treatments develop. There are national recommendations for screening newborns, and each state decides which ones to include. 

Typically, the following conditions are tested for:

Metabolic issues. Metabolism is the bodily function that converts food to energy for growth, intellect, and movement. Special proteins help metabolism by increasing the speed at which chemicals react in the cell. Most problems with metabolism occur when those special proteins are missing or not working correctly. 

Newborn screening for metabolic disorders may check for:

  • tyrosinemia
  • maple syrup urine disease (MSUD) 
  • phenylketonuria (PKU)
  • citrullinemia
  • methylmalonic acidemia
  • medium-chain acyl CoA dehydrogenase (MCAD) deficiency

Problems with hemoglobin. The protein in red blood cells that carries oxygen through the body is called hemoglobin. Hemoglobin medical deficiencies that are tested in newborns include:

Hormonal issues. Chemical “messengers” made by the glands are called hormones. Medical problems with hormones occur when a gland makes too many or not enough. 

Screening for hormonal problems in newborns may check for:

  • congenital adrenal hyperplasia
  • congenital hypothyroidism

Additional tests. Rare but serious medical conditions that may also be included in a newborn screening include:  

  • spinal muscle atrophy (SMA)
  • cystic fibrosis
  • mucopolysaccharidosis type  
  • galactosemia
  • severe combined immunodeficiency (SCID)
  • X-linked adrenoleukodystropy
  • biotinidase deficiency
  • Pompe disease (type II glycogen storage disease)

Most states will also test for congenital heart disease and hearing loss. If you feel your baby should be screened for tests not offered through your state's program, let your doctor know.

A blood sample will be taken from your baby's heel to be tested. That should happen before the baby leaves the hospital after one or two days. You should speak to your doctor immediately if your baby did not receive newborn screenings; for example, if you had a home birth. 

There are three different parts to newborn screening:

  • Blood tests: Most of the screening done on a newborn is a with a blood test to check for potential conditions. You should speak to the hospital staff or your doctor about their specific timeframes for sending blood and getting results back.
  • Heart screening: A heart test is used to check your baby for a group of heart illnesses called critical congenital heart defects. The test that is used is called pulse oximetry. Pulse oximetry checks your baby's blood for its oxygen levels using a machine and sensors placed on the skin.
  • Hearing screening: A test is done to check for hearing loss. In this test, the medical specialist places tiny earphones in the baby's ears and uses a computer to see how your baby responds to sound.

After 24 hours post-birth the first blood test should be taken. Some states retest babies after two weeks.

Newborn screening results for heart disease and hearing loss are available immediately after the test is done. Blood test results usually take 5 to 7 days. Many times, a parent will not hear about the results of the test if they were normal. Instead, they will be contacted only if a condition was detected. If some aspect of the test is positive, though, it does not necessarily mean the baby has a medical condition. Additional diagnostic testing is needed.

If the diagnostic testing confirms that a medical condition has been inherited, doctors may send the baby to a pediatric specialist for additional testing and treatment. If treatment is needed, it must begin as soon as possible. 

Treatment could include:

  • medicines
  • diet
  • restrictions
  • special formula
  • close monitoring
  • supplements

Most newborn screening results are normal. If not, more testing will determine if there is a medical problem. 

Whether diagnostic tests are positive or negative, your doctor will guide you regarding the next steps for your baby.