Blood tests during pregnancy

During pregnancy you'll be offered blood tests to help protect your health and the health of your baby. These tests form an important part of your care.

Benefits of having blood tests in pregnancy

Having these tests could help you make decisions about your care and the care of your baby, both before and after birth.

It's your choice whether to accept these tests or not and it won't affect the quality of your care.

When will I have these tests?

Most of the tests can usually be done at one time, and the midwife will usually take blood from your arm at one of your first visits.

How blood tests are done

What will my blood be tested for?

Your blood will be tested for:

  • blood count, blood group and Rhesus status (positive or negative)
  • sickle cell and thalassaemia
  • infectious diseases (hepatitis B, syphilis and HIV)
  • Down’s syndrome
  • Edwards' syndrome
  • Patau's syndrome

Blood count, blood group and Rhesus status

During your pregnancy you'll be offered a blood test to:

  • measure the level of haemoglobin in your blood (blood count)
  • find out your blood group (A, B, O or AB)
  • find out if you're Rhesus (RhD) positive or RhD negative

More about blood count, blood group and Rhesus status

Sickle cell and thalassaemia

Sickle cell and thalassaemia are serious, inherited blood disorders that are passed on from parents to children through altered haemoglobin genes.

People who have these conditions will need specialist care throughout their lives.

Screening for sickle cell and thalassaemia

Infectious diseases

You'll be offered blood test for infections that can affect you and your baby, such as hepatitis B, syphilis and HIV.

We screen for these conditions because simple treatments can reduce the risks to you and your baby.

Screening for infectious diseases

Down's syndrome

A small number of babies are born each year with Down’s syndrome. You may choose to have tests during pregnancy which can help to detect if your baby may have Down's syndrome. This will either be a blood test or a combined blood test and scan.

Screening for Down's syndrome

Edwards’ syndrome

In the UK, around 1 baby in every 5000 births has Edwards’ syndrome. It’s the second most common chromosomal condition. You may choose to have tests during pregnancy which can help to detect if your baby may have Edwards’ syndrome. This will either be a blood test or a combined blood test and scan.

Screening for Edward’s syndrome

Patau’s syndrome

In the UK, around 1 baby in every 16,000 births has Patau’s syndrome. You may choose to have tests during pregnancy which can help to detect if your baby may have this Patau’s syndrome. This will either be a blood test or a combined blood test and scan.

Screening for Patau’s syndrome

Blood test results

You'll usually be able to get the results at your next clinic visit.

Occasionally technical problems can occur and you'll be asked to have another sample taken. Some tests are also routinely repeated later in pregnancy.

If further investigation is needed, you'll be contacted as soon as possible and given advice and care.

All results are confidential.

What happens to my blood samples after testing is complete?

Any of your leftover blood samples will be stored in the laboratory for at least 12 months. This is so that they can be used in the future if any test results need to be checked.

Medical research

Your leftover blood samples may be used anonymously for other monitoring and laboratory purposes, such as comparing different screening methods and developing new tests. Sometimes leftover blood samples are also used anonymously for education and research to improve the quality of patient care.

Sometimes samples may need to be used that aren't anonymous, in which case you'll always be asked for your consent. If you don't want your stored blood samples to be used for research, please ask the midwife to write ‘no research’ in the comments box on the request form. 

More about how the NHS stores, uses and shares your information