Newborn Testing and What They Mean

In this post I will describe newborn tests that are done in the hospital, what they mean and why they are done. All hospitals and all states are different, so this is what we do in Maryland. Most states will be similar but might have slight differences. You can always email me with questions!

Hearing Screening: 

  • This is done on every newborn anywhere from 12-48 hours old and must be done before going home.
  • This test DOES NOT guarantee hearing problems, just that follow up should be done.
  • The test consists of a small probe inserted into each ear. It then emits a resonance sound and tests the newborns ability to hear it.
  • Your nurse will tell you if your baby passed and there should be no issues.
  • If your baby continues to fail it could be any number of things:
    • Fluid buildup from birth (amniotic fluid). This is especially common with with c section babies who are unable to use the birth canal to clear their ears.
    • All this means is that you will follow up with an audiologist after you take your baby home for further testing.

Congenital Heart Defect Screening: 

  • This is done on every newborn before going home.
  • This test includes getting pulse oxygen on their hand and then on their foot. We do this to screen for congenital heart defects. The test takes only a few minutes.
  • If a baby has a congenital heart defect, hand or foot oxygen level will be low and they will be very different.
  • If a baby fails this test, a echocardiogram will be ordered (this is an ultrasound of the heart to check for defects)
  • If a defect is identified, you will follow up with a cardiologist and possibly a pediatric cardiac surgeon.

PKU Blood Screening: 

  • This is a blood test done when your baby is about 36 hours old that screens for metabolic disorders. This includes things like diabetes, gland issues, etc. The results will be sent out to an outside lab and the results will be sent to your pediatrician for follow up if necessary.
  • This is done by pricking your baby’s heel and drawing blood through that.
  • This is one of the most invasive tests done so parents worry about pain, but babies generally respond well and minimal brushing occurs.

Bilirubin Blood Screening: 

  • This is a blood test drawn at the same time as the PKU screening. This blood is sent to the hospital lab and tests for bilirubin levels in the blood.
  • High bilirubin levels basically means your baby is jaundice. This occurs when they are unable to break down liver waste and can occur because of blood incompatibilities or dehydration.
  • IT IS VERY COMMON in first few days and is treated with phototherapy.

Car Seat Test: 

  • This is done only if your baby is born early (before 37 weeks) or your baby is born small or large for their age.
  • The test consists of measuring their pulse ox level for 90 minutes while in their car seat.
  • This is done because often young or babies with abnormal weights have difficulty maintaining their oxygen levels when seated in a car seat posture.
  • This is LEGALLY required before discharge for any baby meeting the requirements.
  • If your baby was to fail (uncommon), a new car seat must be obtained before the hospital can allow you to take them home.

Blood Sugars: 

  • This is done again only if your baby qualifies for the test. Qualifications include small or large for age or if you yourself had gestational diabetes.
  • Heel sticks will be done before each feeding for 12 hours (for gestational diabetes) or for 24 hours (small or large for age). This is done with a glucometer just as an adult glucose test is done.
  • Sometimes these babies can have difficulty maintaining their sugar levels. If they become too low consistently, it is possible that your baby may need to be transferred to the NICU for IV fluids.


  • This is a urine test done on your baby if your to screen tests positive for anything. This is done by placing gauze or a bag in the baby’s diaper to collect urine.
  • This is done to monitor for signs of withdrawal if needed and have social work visit with you and your baby before you are discharged home to identify any problems.


These are the most common screenings done in the hospital but of course others can happen! If you have questions about any tests not included here, please feel free to email me!


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