Medical Conditions

Abnormal Newborn Screening Results

Content reviewed against published AAP, NIH, March of Dimes guidelines

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If your baby has been diagnosed with or you suspect abnormal newborn screening results, here is what the evidence says.

The short answer

An abnormal or positive newborn screening result means that further testing is needed, not that your baby definitely has a condition. Most positive screens turn out to be false positives after confirmatory testing. Newborn screening tests are intentionally sensitive to avoid missing any affected babies, so follow-up testing is essential to determine whether the result is a true positive.

Key takeaways

  • An abnormal or positive newborn screening result means that further testing is needed, not that your baby definitely has a condition. Most positive screens turn out to be false positives after confirmatory testing. Newborn screening tests are intentionally sensitive to avoid missing any affected babies, so follow-up testing is essential to determine whether the result is a true positive.
  • Usually normal when: You received a callback about a positive newborn screen but confirmatory testing came back normal (false positive)
  • Call your doctor if: You were told your baby's newborn screening showed a critical result that requires immediate follow-up (such as galactosemia or congenital adrenal hyperplasia), as delays in treatment can be life-threatening
  • Varies by age — see the age-by-age breakdown below
“Fever itself is not an illness — rather, it is a sign or symptom that the body is fighting an infection. Fever stimulates certain defenses, such as the white blood cells, which attack and destroy invading bacteria.”
— Fever and Your Child, American Academy of Pediatrics (AAP)

Parents everywhere have the same worry. You are doing the right thing by looking into it.

By Age

What to expect by age

0-48 hours

The newborn screening blood test (heel prick) is typically performed between 24-48 hours after birth. It screens for a panel of conditions including metabolic disorders, endocrine disorders (such as congenital hypothyroidism and congenital adrenal hyperplasia), hemoglobin disorders (such as sickle cell disease), and cystic fibrosis. A hearing screen and pulse oximetry screening for critical congenital heart defects are also performed. Samples collected too early (before 24 hours) may need to be repeated because some conditions are not detectable until the baby has been feeding for a sufficient time.

2-7 days

Results from the newborn screen typically come back within 3-7 days, though timing varies by state. If you are contacted about an abnormal result, try not to panic. The majority of abnormal newborn screening results are false positives, meaning the baby does not actually have the condition. However, it is crucial to follow up promptly with the recommended confirmatory testing. Your pediatrician or a specialist will coordinate the next steps, which may include repeat blood tests, genetic testing, or specialist evaluation.

1-4 weeks

Confirmatory testing is usually completed during this period. For metabolic disorders, this may involve specialized blood and urine tests. For congenital hypothyroidism, thyroid function tests will be checked. For cystic fibrosis, a sweat chloride test is the gold standard confirmatory test but is typically performed after 2 weeks of age when the baby is large enough to produce sufficient sweat. If a condition is confirmed, early treatment can begin, which is the entire purpose of newborn screening. Most screened conditions have much better outcomes when caught and treated early.

1-3 months

If a condition was confirmed, your baby will likely be connected with a specialist (such as a geneticist, endocrinologist, or pulmonologist) and a treatment plan will be in place. For conditions like congenital hypothyroidism, medication started early leads to normal development. For metabolic disorders, dietary management may be required. Regular follow-up visits will monitor your baby's growth, development, and response to treatment. If confirmatory testing was negative, you can be reassured that the initial screen was a false positive.

What Should You Do?

When to take action

Probably normal when...
  • You received a callback about a positive newborn screen but confirmatory testing came back normal (false positive)
  • Your baby needed a repeat heel prick because the first sample was collected too early (before 24 hours of age)
  • Your baby's screen was borderline, a repeat test was normal, and no further follow-up is needed
  • All newborn screening results came back normal and no further action is required
Mention at your next visit when...
  • You received an abnormal newborn screening result and have not yet scheduled follow-up testing
  • You are unsure about the results or have not received your baby's newborn screening results
  • Your baby has a confirmed condition from newborn screening and you have questions about long-term management
Act now when...
  • You were told your baby's newborn screening showed a critical result that requires immediate follow-up (such as galactosemia or congenital adrenal hyperplasia), as delays in treatment can be life-threatening
  • Your baby is showing symptoms such as poor feeding, vomiting, lethargy, seizures, or unusual odor, which could indicate a metabolic emergency, especially if an abnormal screen result is pending

Doctor Visit Checklist

Bring this checklist to your next pediatrician visit to discuss Abnormal Newborn Screening Results.

Things to mention

  • You received an abnormal newborn screening result and have not yet scheduled follow-up testing
  • You are unsure about the results or have not received your baby's newborn screening results
  • Your baby has a confirmed condition from newborn screening and you have questions about long-term management

Observations to share

  • You received an abnormal newborn screening result and have not yet scheduled follow-up testing
  • You are unsure about the results or have not received your baby's newborn screening results
  • Your baby has a confirmed condition from newborn screening and you have questions about long-term management

Urgent signs to report immediately

  • You were told your baby's newborn screening showed a critical result that requires immediate follow-up (such as galactosemia or congenital adrenal hyperplasia), as delays in treatment can be life-threatening
  • Your baby is showing symptoms such as poor feeding, vomiting, lethargy, seizures, or unusual odor, which could indicate a metabolic emergency, especially if an abnormal screen result is pending

My notes

From ismybabyalright.com — free, evidence-based baby health guides

Milestone

Month-by-Month Development

Detailed monthly development guides from birth through 24 months.

Guide

When to Call the Doctor

General guide on when to call the pediatrician, visit urgent care, or go to the ER.

Frequently asked questions

Is abnormal newborn screening results normal?
An abnormal or positive newborn screening result means that further testing is needed, not that your baby definitely has a condition. Most positive screens turn out to be false positives after confirmatory testing. Newborn screening tests are intentionally sensitive to avoid missing any affected babies, so follow-up testing is essential to determine whether the result is a true positive.
When should I call the doctor about abnormal newborn screening results?
You were told your baby's newborn screening showed a critical result that requires immediate follow-up (such as galactosemia or congenital adrenal hyperplasia), as delays in treatment can be life-threatening Your baby is showing symptoms such as poor feeding, vomiting, lethargy, seizures, or unusual odor, which could indicate a metabolic emergency, especially if an abnormal screen result is pending
When is abnormal newborn screening results normal?
You received a callback about a positive newborn screen but confirmatory testing came back normal (false positive) Your baby needed a repeat heel prick because the first sample was collected too early (before 24 hours of age) Your baby's screen was borderline, a repeat test was normal, and no further follow-up is needed
What causes abnormal newborn screening results?
An abnormal or positive newborn screening result means that further testing is needed, not that your baby definitely has a condition. Most positive screens turn out to be false positives after confirmatory testing. Newborn screening tests are intentionally sensitive to avoid missing any affected babies, so follow-up testing is essential to determine whether the result is a true positive. Common explanations include: You received a callback about a positive newborn screen but confirmatory testing came back normal (false positive). Your baby needed a repeat heel prick because the first sample was collected too early (before 24 hours of age).
What should I mention to my pediatrician about abnormal newborn screening results?
You should mention abnormal newborn screening results at your next visit if: You received an abnormal newborn screening result and have not yet scheduled follow-up testing. You are unsure about the results or have not received your baby's newborn screening results. Your baby has a confirmed condition from newborn screening and you have questions about long-term management.
Is abnormal newborn screening results normal at 0-48 hours?
The newborn screening blood test (heel prick) is typically performed between 24-48 hours after birth. It screens for a panel of conditions including metabolic disorders, endocrine disorders (such as congenital hypothyroidism and congenital adrenal hyperplasia), hemoglobin disorders (such as sickle cell disease), and cystic fibrosis. A hearing screen and pulse oximetry screening for critical congenital heart defects are also performed. Samples collected too early (before 24 hours) may need to be repeated because some conditions are not detectable until the baby has been feeding for a sufficient time.
Is abnormal newborn screening results normal at 2-7 days?
Results from the newborn screen typically come back within 3-7 days, though timing varies by state. If you are contacted about an abnormal result, try not to panic. The majority of abnormal newborn screening results are false positives, meaning the baby does not actually have the condition. However, it is crucial to follow up promptly with the recommended confirmatory testing. Your pediatrician or a specialist will coordinate the next steps, which may include repeat blood tests, genetic testing, or specialist evaluation.
Should I go to the ER for abnormal newborn screening results?
Seek emergency care if you were told your baby's newborn screening showed a critical result that requires immediate follow-up (such as galactosemia or congenital adrenal hyperplasia), as delays in treatment can be life-threatening, or if your baby is showing symptoms such as poor feeding, vomiting, lethargy, seizures, or unusual odor, which could indicate a metabolic emergency, especially if an abnormal screen result is pending. When in doubt, call your pediatrician's after-hours line for guidance.
Does abnormal newborn screening results go away on its own?
In many cases, abnormal newborn screening results resolves on its own, especially when you received a callback about a positive newborn screen but confirmatory testing came back normal (false positive). By 1-3 months, if a condition was confirmed, your baby will likely be connected with a specialist (such as a geneticist, endocrinologist, or pulmonologist) and a treatment plan will be in place. For conditions like congenital hypothyroidism, medication started early leads to normal development. For metabolic disorders, dietary management may be required. Regular follow-up visits will monitor your baby's growth, development, and response to treatment. If confirmatory testing was negative, you can be reassured that the initial screen was a false positive.
AAPNIHMARCH OF DIMES

References

  1. [1]American Academy of Pediatrics. Newborn Screening. HealthyChildren.org. AAP
  2. [2]National Institutes of Health. Newborn Screening. MedlinePlus. NIH
  3. [3]March of Dimes. Newborn Screening Tests for Your Baby. March of Dimes

All content follows our editorial policy and is reviewed against published clinical guidelines.

2,705 evidence-based guides6 authoritative medical sources

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Bottom line

Most cases of abnormal newborn screening results are normal. Talk to your pediatrician if you were told your baby's newborn screening showed a critical result that requires immediate follow-up (such as galactosemia or congenital adrenal hyperplasia), as delays in treatment can be life-threatening.

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.

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