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Newborn Pulse Oximetry Screening

What is pulse oximetry?

Pulse oximetry (sometimes called “pulse ox”) is a simple and painless test that can measure your baby’s oxygen levels in the blood.

How does it work?

Your baby’s blood oxygen levels are measured by placing an adhesive strip around your baby’s thumb, wrist, hand, toe or foot. The strip has a red light on it that shines through the baby’s skin. The strip is then attached to a monitor (called a “pulse oximeter”) by a long wire or cord. Shortly after the strip has been placed on your baby’s skin, a number will appear on the monitor that gives your baby’s doctor information about the amount of oxygen in your baby’s body. The test usually takes only a few minutes, but the baby must be quiet and still to get accurate information. If the baby is squirming or crying, the test can take longer.

Can the pulse oximeter hurt my baby?

The pulse oximeter is only connected to your baby by the adhesive strip, and usually does not cause any type of pain or discomfort.

Why does my baby need this test?

Pulse oximetry can help your doctor to be sure that your baby’s heart and lungs are healthy and supplying enough oxygen to their body. The test can also help to find out if your baby may have a serious heart problem that may not be obvious in the first days of life. Finding an unexpected heart problem early will help your baby’s medical team give special care to your baby and prevent harm caused by the heart problem. These heart problems are known as congenital heart defects (CHD). For the small number of babies who do have CHD it is extremely important that their problem be detected as early as possible so that they receive the safest and best care. The American Heart Association, the American Academy of Pediatrics, and the National Institutes of Health all recommend screening for congenital heart disease by pulse oximetry in all newborns.

What is a congenital heart defect?

Congenital heart defect or disease (CHD) is a problem with the structure of the heart or the way in which blood flows through the heart. CHD is the most common serious birth defect that babies can have, and the cause is often unknown. Pulse oximetry may be the first clue to the presence of CHD.

The names of some of these are:

  • Hypoplastic left heart syndrome
  • Pulmonary atresia (with intact septum)
  • Tetralogy of Fallot
  • Total anomalous pulmonary venous return
  • Transposition of the great arteries
  • Tricuspid atresia
  • Truncus arteriosus

If your baby is diagnosed with any of these defects, your baby’s cardiology team will provide you with more information about what this means
for you and your baby.

Last reviewed 8/2015

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This page is not specific to your child, but provides general information on the topic above. If you have any questions, please call your clinic. For more reading material about this and other health topics, please call or visit Children's Minnesota Family Resource Center library, or visit

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