A pulse oximetry test is a simple and routine check offered to all newborns within their first 24 hours. This quick test helps monitor your baby’s blood oxygen levels.
Below you will find answers to common questions, and your medical team is always happy to provide more details or address any concerns you may have.
What is a pulse oximetry test?
A pulse oximetry test measures the oxygen levels in your baby’s blood. It is non-invasive and uses a light sensor. The test takes a few minutes at no discomfort to your baby.
Why is my baby having a pulse oximetry test?
This test will help find the small number of babies who have medical problems that can cause their oxygen levels to be lower than normal. Some babies with lower oxygen levels can look perfectly healthy after birth, which is why the test is carried out. It will measure the level of oxygen in your baby’s blood (also known as oxygen saturations), so those who have lower than expected levels can be referred for further investigations.
What happens during the test?
To measure your baby’s oxygen saturations, your healthcare provider will wrap a sensor around your baby’s right hand. The sensor is connected to the pulse oximeter device, which shines a light through your baby’s skin to measure the blood oxygen level. The sensor will then be wrapped around your baby’s foot to take a second reading. The test is painless and should take no more than five minutes.
What if my baby’s oxygen levels are normal?
If your baby’s oxygen levels are normal, they won’t need any further pulse oximetry testing at this time. Your baby will receive all the usual care before being discharged from hospital, including their routine newborn examinations.
While a normal result is reassuring, it doesn’t rule out the chance of a problem developing. If you have any concerns about your baby – for example concerns about their temperature, colour, feeding, appearance or energy levels , please seek urgent medical advice.
What if my baby’s oxygen levels are lower than normal?
There are two main reasons why a newborn might show lower-than-expected oxygen levels:
- Slightly low oxygen levels (around 3 in every 100 babies):
Some babies’ lungs take a little longer to adjust after birth, which is completely normal. If your baby’s oxygen level is only a little below the usual range and they seem otherwise healthy, the test will be repeated in about one to two hours. This follow-up check is called a retest. - Significantly low oxygen levels (around 3 in every 1,000 babies):
If your baby’s oxygen level is much lower than expected, they’ll be seen immediately by a doctor or specialist nurse. Further checks and tests will be carried out to understand the cause and ensure your baby gets the right care.
What happens if my baby needs a retest?
In most cases (90%), babies who need a second check will have normal oxygen levels when retested, and no further action is required. Because of the need to confirm normal levels before discharge, this extra test may occasionally mean a small delay in going home.
What will happen if my baby needs further examination or treatment?
Including both initial tests and retests, around 7 in every 1,000 babies (0.7%) will require further investigation. These babies are usually admitted to the Neonatal Unit – sometimes called the Baby Unit, Neonatal Intensive Care Unit (NICU), or Special Care Baby Unit (SCBU). Parents can visit their baby on the unit, and the medical team will explain what is happening at every stage.
On the Neonatal Unit, babies may undergo blood tests and X-rays to identify the reason for low oxygen levels. Some may also have an ultrasound of the heart, known as an echocardiogram (or echo).
Of the babies admitted:
- 2 in 10 are healthy and typically stay for less than 12 hours.
- 7 in 10 have a breathing problem or infection, benefiting from early diagnosis and treatment.
- 1 in 10 will have a heart condition or another underlying issue requiring specialist care.
What if my baby is born at home?
All babies born at home will receive a pulse oximetry test, though the timing may differ slightly from hospital births. The test will still be carried out within the first 24 hours of life, which is the recommended timeframe for accurate results.
If a home test shows oxygen levels that are only slightly below normal, your baby will need a retest. In some cases, parents may need to bring the baby to hospital for this, as a midwife might not be able to return to perform the second test.
If the initial test shows oxygen levels that are significantly lower than expected, the baby may need to go to hospital urgently, sometimes within the hour. In certain situations, an ambulance transfer may be required. At the hospital, your baby will be assessed immediately by a doctor or specialist nurse.
What should I do if I have questions about my baby’s pulse oximetry test?
If you have any questions, please ask any of the team who are looking after you.
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