Newborn screening tests look for serious developmental and genetic disorders so that important action can be taken during the critical time before symptoms develop.

In the U.S., the individual states each regulate newborn screening, so the diseases screened vary considerably. Most states require three to eight tests, but organizations such as the March of Dimes suggest more than two dozen additional tests. The most thorough screening panel checks for about 40 disorders. All 50 states screen for congenital hypothyroidism.

Infant screening tests

Blood tests: A health care professional will prick the baby’s heel to obtain a drop or two of blood. The blood is sent to a lab for analysis.

Hearing test: An audiologist will place a tiny earpiece or microphone in the infant’s ear or stick electrodes on the baby’s head.

The baby will most likely cry when his or her heel is priced to obtain the small blood sample. The hearing test should not cause the baby to feel pain, cry, or respond.

Screening tests do not diagnose illnesses. They identify which babies need additional testing to confirm or rule out illnesses. Good screening tests have a low false-negative rate (if the test is normal, the child should be healthy), but may have a high false-positive rate (as many affected children as possible should test positive, even if this means many healthy children also test positive).

If a disorder is diagnosed on follow-up testing, appropriate treatment can be started right away, before symptoms appear.

Screening tests are used to detect a number of disorders, including:

• Biotinidase deficiency
• Congenital adrenal hyperplasia
• Congenital hypothyroidism
• Cystic Fibrosis
• Galactosemia
• Glucose-6-phosphate dehydrogenase deficiency (G6PD) 
• Hearing problems
• Hemoglobinopathy Disorders and Traits
• Homocystinuria
• Human immunodeficiency disease (HIV)
• Maple syrup urine disease
• Medium-chain acyl-CoA dehydrogenase (MCAD)
• Sickle cell disease
• Toxoplasmosis

Specific Tests:

• Acylcarnitine profile. This test screens for organic acid and fatty acids disorders, including methylmalonic acidemia (MMA).
• Amino acid profile. This test looks for amino acid deficiencies such as maple syrup urine disease  and phenylketonuria .     
• APGAR. The APGAR test is performed one to five minutes after birth. Observers evaluate heart rate, breathing, activity, and skin color to detect which babies may need extra medical attention in the delivery room.

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Bryant KG, Horns KM, Longo N, Schiefelbein J. A primer on newborn screening. Adv Neonatal Care. 2004 Oct;4(5):306-17.

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Centers for Disease Control and Prevention. Newborn Screening for Cystic Fibrosis: Evaluation of Benefits and Risks and Recommendations for State Newborn Screening Programs. J Pediatr. 2005 Sep;147(3 Suppl):S1.

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