Pregnancy and baby

Screening tests in pregnancy

What happens at a scan and what will they tell me?

Media last reviewed: 20/03/2014

Next review due: 20/03/2016

Screening tests in pregnancy

You will be offered some screening tests during pregnancy to try to find any health problems that could affect you or your baby, such as infectious diseases, Down’s syndrome or physical abnormalities. The tests can help you to make choices about care or treatment during your pregnancy or after your baby is born.

All screening tests offered by the NHS are free.

What are screening tests?

Screening tests are used to find people at higher risk of a health problem. This means they can get earlier, potentially more effective, treatment or make informed decisions about their health. It’s a bit like putting people through a sieve – most people pass straight through, but a small number get caught in the sieve. The people caught in the sieve are those considered to be at a higher risk of having the health problem being screened for.

Screening tests are not perfect. Some people will be told that they or their baby are at high risk of having a health problem when in fact they do not have the problem. Also a few people will be told that they or their baby are at low risk of having a health problem when in fact they do have the problem.

What screening tests are used in pregnancy?

The screening tests offered during pregnancy are either ultrasound scans or blood tests, or a combination of both.

Ultrasound scans may detect physical abnormalities, such as spina bifida. Blood tests can help to find the risk of inherited disorders such as sickle cell anaemia. Blood tests combined with scans can help to find the risk of chromosomal abnormalities such as Down’s syndrome.

What are the risks of screening tests?

Screening tests will not harm you or your baby, but there are some risks to consider. Some screening tests in pregnancy can lead to serious decisions for you. For example, screening tests for Down’s syndrome can lead to difficult decisions about whether to have a diagnostic  test that carries a possible risk of miscarriage.

Diagnostic tests, if positive, can lead to a decision about whether you want to continue or end the pregnancy. Having a further test or termination will always be your decision and health professionals will support you, whatever you decide.

You may want to think carefully about whether or not you want to have these screening tests.

When will I be offered screening?

Different screening tests are offered at different times during pregnancy.
You will be offered screening for Down’s syndrome around the time of your dating scan, which happens when you are around 11 to 14 weeks pregnant.

You will be offered screening for abnormalities at a mid-pregnancy scan when you are around 18-21 weeks pregnant.

Will screening tests give me a definite answer?

No – a screening test does not usually say for certain if you or your baby have a health problem. It tells you if you or your baby are at a high or low risk of having the problem. Women or babies found to be at high risk of a problem will often be offered a diagnostic test. A diagnostic test gives a more definite ‘yes’ or ‘no’ answer.

Do I have to have the screening tests?

No, it’s up to you whether or not to have a screening test. It is a personal choice that only you can make. You can discuss each of the screening tests you are offered with your midwife or doctor and decide whether or not it is right for you.

Some of the screening tests you will be offered are recommended by the NHS, such as:

  • blood tests for infectious diseases
  • eye screening if you have pre-existing diabetes (not gestational diabetes)
  • newborn checks

This is because the results from these tests can help make sure that you or your baby get urgent treatment for serious problems.

What screening tests will I be offered in pregnancy?

You can find out more about each of the different screening tests by clicking on the links here:

  • Screening for infectious diseases (hepatitis B, HIV, syphilis, rubella).
  • Screening for inherited conditions (sickle cell, thalassaemia and other haemoglobin disorders).
  • Screening for Down’s syndrome.
  • Screening for abnormalities (18-21 week scan).

Some screening tests will also be offered to your baby after they are born. You can read more about these tests by clicking on the links here:

  • Newborn physical examination.
  • Newborn hearing screening.
  • Newborn blood spot screening.

Your midwife or GP should give you a booklet about antenatal and new born screening, called Screening tests for you and your baby.


By law, everyone working in, or on behalf of, the NHS must respect your privacy and keep all information about you safe. The NHS Constitution sets out how the NHS should handle your records to protect your privacy. In addition, there are laws in place to ensure confidentiality is maintained.

Screening records are shared only with staff who need to see them. Sometimes information is used for audit research purposes to improve screening outcomes and services. Information will be provided to you when you are screened.

Some private companies also provide screening tests that you have to pay for. The NHS cannot guarantee the quality of private screening. More advice is available at

Page last reviewed: 19/01/2015

Next review due: 19/01/2017


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The 2 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Kathryn at NHS Choices said on 31 January 2014

Dear Froggit61,

You will find information on B-strep in pregnancy in our article on 'Infections in Pregnancy':

Best wishes,
Kathryn Bingham, NHS Choices editor

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Froggit61 said on 21 August 2013

This page has no information on B-strep during pregnancy.
Women are tested for this through a urine sample but are not told they are being tested and therefore have no information on this condition. If the baby is born while the mother is positive B-strep, the baby is at high risk of dying.
Please add B-strep info to this page to save young mother's heartache!

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