Pregnancy and baby

Newborn blood spot screening FAQs

All your questions about newborn blood spot screening answered, including what happens to your baby's blood spot card and why a second sample is sometimes needed.

Why does blood have to be taken when babies are only about a week old?

If a baby's heel is pricked between days five and eight, how is this calculated?

When should premature babies be screened?

When is a second sample needed?

Are any of the conditions tested for during pregnancy?

I have been told my baby is a carrier. What does this mean for my baby and my family?

If we move to a new area, will health professionals need proof that my baby has had the screening test?

What are newborn blood spot cards?

What happens to my baby's blood spot card?

Why does blood have to be taken when babies are only about a week old?

This is the best time to test for all the conditions together. It allows time for getting the results back, to do diagnostic tests if required, and start treatment early.

If babies were tested later, some babies might suffer harm that could have been avoided if they had been tested earlier.

Younger siblings of children affected by one of the conditions can be tested for the specific condition earlier than five days. Another sample can be taken on day five to screen for the other conditions.

If a baby's heel is pricked between days five and eight, how is this calculated?

The calendar day on which your baby is born is considered day zero, no matter what time of day your baby is born. The day after your baby's birth date is day one, and so on.

When should premature babies be screened?

Babies admitted to hospital before day five, perhaps because they are premature or unwell, should have a blood spot sample taken on admission. This sample will be used to screen for sickle cell disease in case the baby has a blood transfusion.

Babies who are premature, unwell, or have had blood transfusions should have a blood spot sample taken as usual between five and eight days. This information is recorded on the blood spot card.

If a baby is born before 32 weeks, an additional test is needed for congenital hypothyroidism at 28 days of age or when they are discharged home from hospital, whichever is sooner.

When is a second sample needed?

Occasionally your midwife or health visitor will contact you and ask to take a second blood sample from your baby's heel. This may be because not enough blood was collected, or the result was borderline or unclear.

It may also be because your baby was premature. In babies born before 32 weeks of pregnancy, testing at about five days may not pick up congenital hypothyroidism. It's advisable to have another test either at 28 days or before your baby is discharged home, whichever comes first. The repeat results are usually normal.

Are any of the conditions tested for during pregnancy?

Women are screened for sickle cell disease during pregnancy. It is possible to screen for cystic fibrosis carriers in pregnancy, but currently this isn't done in the UK.

I have been told my baby is a carrier. What does this mean for my baby and my family?

Carrier status is very common and it doesn't mean your baby will become ill.

For your baby:

  • If your baby is a carrier, he or she will be healthy.
  • Sometimes further tests are needed to confirm cystic fibrosis carrier status. You can arrange these through your GP. See more about being a carrier of cystic fibrosis.
  • Sickle cell disease carrier results are usually more straightforward. Your midwife or GP will tell you if further tests have been recommended and can arrange these. Read more about when your baby carries a gene for sickle cell.

For your family:

  • A baby may be a carrier because one of their parents is. This is quite common and shouldn't affect their health.
  • Rarely, a baby may be a carrier because both their parents are, but they have inherited the gene from only one parent. If both parents are carriers, there is a one in four chance that a future brother or sister may inherit two altered genes. In this case, the baby would have an inherited disease.
  • Currently, women are offered testing for sickle cell disease in pregnancy, so new mothers should already know if they are carriers. A genetic counsellor can explain this in more detail and arrange tests for you if you are concerned.

If we move to a new area, will health professionals need proof that my baby has had the screening test?

If your baby is under one year of age and you move to a new area, you will need to provide confirmation to your GP or health visitor that they have been screened. This could be a faxed or written copy of their results, or results written in the personal child health record. If you have moved from abroad and no proof of testing is available, re-testing can be discussed with you and arranged if you give your consent.

What are newborn blood spot cards?

As well as being used to take blood samples, these cards record personal information including a baby's name, their mother's name, the baby's date of birth, their address, contact details of the GP and midwife, and the baby's NHS number. These are needed to make sure the results of the screening tests are matched to the right baby.

What happens to my baby's blood spot card?

After screening, the blood spot cards, including any remaining (residual) blood spots not needed for the screening tests, are stored for at least five years. They may be used:

  • to double-check the result
  • for other tests recommended by your doctor
  • to improve the newborn screening programme
  • for research to help improve the health of other babies and their families

This research will not identify your baby, and you will not be contacted. The use of these blood spots is covered by a code of practice, which is available from your midwife.

There is a small chance researchers may want to invite you or your child to take part in research linked to this screening programme. If you do not want to be invited to take part in research, please let your midwife know.

It's also important to know that identifiable data on babies affected with sickle cell disease or thalassaemia may be used to improve screening. If you do not wish your baby's screening data to be used in this way, email scts.evaluation@nhs.net or call 020 7848 6627.

You can find out more about why blood spot cards are stored and how your baby's personal information is protected in Newborn blood spot cards explained.

Page last reviewed: 04/02/2025

Next review due: 31/07/2024

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