Why is a test offered for the detection of serious heart problems in newborns?

Photo of a couple talking with a gynecologist (PantherMedia / Katarzyna Bia asiewicz )

Various screening tests are routinely offered during pregnancy and after babies are born. One of those screening tests is known as pulse oximetry. This test detects the majority of serious heart problems before they cause any symptoms, so they can be treated earlier.

A light sensor is used to measure the amount of oxygen in the baby’s blood. Too little oxygen in the baby’s blood could be a sign of a serious heart problem (critical congenital heart disease, or CCHD). Pulse oximetry doesn’t involve taking blood. It also doesn’t hurt and only takes a few seconds.

Why is this test offered?

Despite ultrasound scans during pregnancy and routine check-ups immediately after birth (known as the “U1” check-up in Germany), some serious heart defects might not be detected: This happens in about 4 out of 10,000 babies. Pulse oximetry is offered in order to help find such “undetected” cases as soon as possible.

Defects of the heart or surrounding blood vessels are considered to be "serious" if they affect the blood circulation so much that the child probably wouldn’t survive without treatment. The sooner serious heart problems are treated, the more likely the child is to develop normally.

What does pulse oximetry involve?

The best window of time in which to do this screening test is 24 to 48 hours after birth. To measure the amount of oxygen in the baby’s blood, a sensor is placed on their foot. The sensor is attached to a screen. The results are immediately displayed on the screen.

  • If the blood contains at least 96% of the maximum possible amount of oxygen, the results are considered to be normal.
  • Babies with readings between 90% and 96% are tested again within two hours. If the readings are still below 96%, the baby immediately has further examinations, such as an ultrasound scan of the heart. As a precaution, the baby can be given medication to make sure that his or her body gets enough oxygen.
  • If the initial reading is lower than 90%, the baby immediately has further examinations (without repeating the pulse oximetry test) and treatment is started if necessary.

How reliably are serious heart defects detected?

A large study carried out in Germany provides a rough idea of what can be expected if babies are screened using pulse oximetry tests after birth in addition to having the routine “U1” check-up.

  • An average of about 3 out of 10,000 serious heart defects will be discovered thanks to the pulse oximetry test.
  • Roughly 1 out of 10,000 serious heart defects still won’t be detected despite doing the pulse oximetry test.


Illustration: At a glance: What happens if 10,000 babies have a pulse oximetry test?

It’s important to be aware that abnormal readings don’t necessarily mean the baby has a heart problem. Low oxygen levels might be caused by something else, such as an infection or lung disease.

Does pulse oximetry have disadvantages?

The test doesn’t have any side effects itself, so it can’t harm the child. But if the readings are considered to be abnormal, further tests might have to be done. The time spent waiting to find out if the baby has a heart problem can be distressing for parents.

Where is the test carried out?

Pulse oximetry tests are offered in all hospitals with maternity units. Women who don’t give birth in a hospital can talk about other pulse oximetry options with their midwife or birth attendant.

What happens if you decide not to make use of the test?

Pulse oximetry screening is voluntary. If parents don’t want their baby to have the test, there won’t be any insurance-related consequences. Should a heart problem be discovered at a later time, statutory health insurers in Germany will still cover the costs of any necessary treatments.

More information

Before the test is done, you will be able to talk it over with a medical professional. Those who already have questions beforehand can contact their maternity unit, obstetrician/gynecologist, midwife or birth attendant.