Newborn Screening Tests: Which One They Will Get and Why

As a new parent, you may be wondering, “What is newborn screening for?” Newborn screening tests take place in all hospitals across the US, and it is done to determine your baby’s health condition.

Screening tests are generally done quickly and painlessly and you will be able to obtain the results either immediately or within a few days, depending on the test.

What is Newborn Screening?

Newborn screening tests are done on a baby within a day or two after birth to make sure that there are no serious conditions. If babies are found with certain conditions, doctors can start treatment as soon as possible.

When scientist Robert Guthrie (in the 1960s) developed a certain type of blood test that could easily detect if a newborn had a metabolic disorder known as phenylketonuria (PKU), it led to the start of newborn screening. Today screening is done for more than 60 conditions or disorders. In the US, screening is part of the public health service and mission.

In the US, the Advisory Committee on Heritable Disorders in Newborns and Children recommends 35 conditions to be screened and most states screen for at least 29. Conditions for screening may differ between each state.

Why is Screening Important?

The screening tests are done within 48 hours before the baby has any observable symptoms. This allows for potential conditions to be identified so that treatment is given before the problem occurs.

In other words, a screening test will not rule out or confirm a condition. It is used to identify babies who have the possibility of the condition. In case a positive screen is found, you as the parents will be notified and this allows for follow-up testing to be done.

Babies, who appear to be normal at birth, might have some underlying disease. Without any screening, it may be hard to identify in time and this could lead to irreversible damage. Diseases for which screening tests are done are related to developmental disabilities, recurrent illnesses, and in rare circumstances, death.

Identifying problems early on (as soon as your baby is born) helps to save time and helps in making the correct diagnosis. 

When and where do screening tests take place?

If your baby is born in a hospital, the hospital will conduct screening tests. The medical staff is well-equipped to handle the blood tests to send for analysis and to handle heart and hearing tests. In case you and your baby leave the hospital before 24 hours have passed since birth, you may need to return to the hospital within one or two weeks to finish the testing.

If your baby is born at home, your doula or midwife might have the qualifications to do the blood and hearing test. Alternatively, you can take your baby to a healthcare provider, or to a local hospital, or a clinic, in the first few days after birth for the screenings to be done.

How is Newborn Screening Done?

Typically, there are three parts to a screening process for newborns.

First, when a baby is between 24 and 48 hours old, a blood test is performed. A heel stick is used to collect the baby’s blood sample. Second, a pulse oximetry is done which helps to determine the amount of oxygen in your baby’s blood and third, a hearing screening is done.

The blood test is always done before 24 hours because if the blood sample is not drawn at the correct time, some conditions can go undetected.

Common Screening Tests

In general, screening tests for newborns include the following:

Tests for metabolic issues

Metabolism is the process of conversion of food into energy in the body. Since enzymes help to increase the chemical reactions in the body, metabolic problems take place when enzymes are absent or not working in the right way. In newborn screenings, metabolic disorders cover the following:

  • Phenylketonuria (PKU) - This is a hereditary disease that does not allow one’s body to metabolize a certain type of protein.
  • Tyrosinemia- A genetic disease that disrupts the processes of the breakdown of tyrosine, which is an amino acid, a major building block of most proteins.
  • Galactosemia- This disease prevents newborns from metabolizing a particular type of sugar that is found in milk.
  • Homocystinuria- An enzyme disease that leads to other health issues.
  • Methylmalonic academia- This occurs when the body can’t break down certain fats and proteins. It can lead to the buildup of methylmalonic acid in the blood and is a hereditary disease.
  • Medium Chain acyl CoA dehydrogenase (MCAD) deficiency- It is a genetic disease that prevents certain fats from breaking down in the body. The level of sugar in the blood can drop very low, which can be dangerous.
  • Maple Syrup Urine Disease (MSUD) - This disease gets its name from the sweet-smelling urine in infants. It is a metabolic disorder that affects branched-chain amino acids.

Tests for Hormonal problems 

Hormones are made by the glands in our body, and they are responsible for sending chemical messages. Sometimes a hormonal imbalance can occur when a gland makes too much or too little of a particular hormone. Hormonal screenings in newborns include:

  • Congenital hypothyroidism- This occurs when there is a radical decrease of the thyroid hormone in newborns. Results are stunted growth, physical deformities, and neurological dysfunction.
  • Congenital adrenal hyperplasia (CAH) - This is a hereditary disease that is marked by a deficiency of an enzyme that is required to make a certain hormone.  It is a disease related to the adrenal glands.

Hemoglobin issues

Hemoglobin is the protein in red blood cells which carry oxygen throughout our body. Problems associated with it are:

  • Sickle cell disease- This is a severe form of anemia.
  • Hemoglobin SC disease- It is a type of sickle cell disease and affects the shape of red blood cells.
  • Beta-thalassemia- This disease is a blood disorder that decreases the production of hemoglobin.

Hearing tests 

Hearing tests are simple to do and take between five and ten minutes. It can be done even when a baby is sleeping. If there is an issue with your baby’s hearing, you will be referred to a pediatric audiologist.  This specialized doctor will help to find out if your baby has a loss of hearing. Babies can be screened for one or both of the following tests:

  • Otoacoustic emissions (OAE) - For this test, soft earphones along with a microphone are placed in the baby’s ear. The earphone is responsible for playing a sound, and the microphone measures and picks up the ear’s response.
  • Auditory brain stem response- Earphones are placed in your baby’s ear and a sound is made. Three electrons are placed on your baby’s head to measure how the brain stem and auditory nerve respond.

Screening for heart defects 

For heart issues, the pulse oximetry test will determine the amount of oxygen in a baby’s blood. Painless sensors are placed on the baby’s hand and foot only for a few minutes. Sometimes, the initial screening test shows that there is low blood oxygen, so your baby will be tested once again about one or two hours later.

If the device continues to show low oxygen levels, an echocardiogram may be advised. If the condition is severe, you may be referred to a pediatric cardiologist for additional tests like a chest X-ray or an EKG.

When Are the Results Available?

When a screening test for heart disease or hearing is done, the results are available immediately. Blood test results will usually be available within 5 to 7 days after the test, but you may not hear about it if the test was normal.

Further tests are conducted only if the screening was positive for a particular condition. But this does not mean that your child definitely has a medical condition. In case a diagnosis is confirmed, your doctor may refer your baby to a specialist for additional treatment or testing. Treatment often includes diet restrictions, specialized formula, medicines, supplements, and monitoring.

What happens if the Tests are not Normal?

If the initial tests are not normal, you need not worry about it. It just means that further testing is required to find out whether there is a disorder. It does not mean that your baby has a disorder for sure.

In certain cases, a baby’s screening tests may show that they are not normal if the test is taken too soon after the baby is born, or if there is fluid in the baby’s middle ear (for the hearing test), or if not enough blood is collected when doing the test. Or it could mean that your baby is a carrier of a disease without necessarily having the disease (example - cystic fibrosis).

Sometimes it may turn out that your baby has a health issue, but diagnosing it early on will give you a chance to rectify the problem with medication or a change in diet. Do not leave any condition untreated as this could lead to organ damage, further illnesses, and even death.

Is it Possible to Choose Which Screening Tests to Perform?

In some states, screening tests at birth for all newborns are mandatory. In other states, as parents, you may opt to not do certain tests due to personal or religious reasons. The government advises that testing for all babies is very important. If you have any questions regarding screening tests before they are done, you can always ask your healthcare provider.

Additional testing (beyond what is legally needed) may require fees. Certain tests may be covered by your health insurance, but it is always advisable to speak to your insurance agency first.

The Bottom Line

If you have any questions regarding the screening tests, your healthcare provider and medical stall in the hospital will surely be able to help you. Screening tests are important and give you peace of mind. Should anything be wrong with your baby, you can always seek medical intervention for your child.


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