Types of pregnancy screening tests

You'll be offered the following kinds of tests:

• questions about your health and family history - this is usually done by your midwife
• blood tests to check for infectious diseases and anaemia and your blood group - this is usually done at your booking visit in the hospital or with your midwife
• a dating ultrasound scan - this helps your obstetrician and midwife to work out when your baby is due

Blood tests

Most obstetricians, GPs and midwives would strongly recommend you have blood tests.

Blood tests can identify whether you need any urgent treatment. This could prevent you and your baby becoming very ill, and could also prevent your baby from having a disability or even dying.

Tests for sickle cell disease and thalassaemia

You might be offered extra blood tests to check for sickle cell disease and thalassaemia.

You're more likely to be offered this test if you or your family come from parts of the world where these diseases are more common, such as:

• the Mediterranean
• Africa
• the Caribbean
• India
• Pakistan
• other parts of Asia

'Anomaly' scans

You might be offered a mid-pregnancy ultrasound scan at around 18 to 21 weeks. It's sometimes called an 'anomaly' scan or a 'fetal anatomy' scan.

This scan checks for physical abnormalities in the baby.

Fetal anatomy scan

Gestational diabetes screening

You might be offered screening for gestational diabetes - it's usually done in your maternity hospital.

In some maternity hospitals this test is offered to all women. In other areas it is only offered to women who have other risk factors for gestational diabetes.

Tests for chromosomal problems

You might be offered a screening test to check if your baby has a chromosomal problems such as Down syndrome, Edwards’ syndrome and Patau’s syndrome.

You'll be offered this if your baby is at increased risk. For example, because of your age or because you previously had a baby with one of these syndromes.

If the results show that there's a high risk of your baby having one of these conditions, it can lead to you having to make very difficult decisions about whether you want to continue with the pregnancy.

You also may have to make a decision whether to have a diagnostic test which could have a risk of miscarriage.

Non-invasive prenatal testing (NIPT)

Non-invasive prenatal testing (NIPT) is a common type of screening test for chromosomal problems.

Examples of NIPT are the Panorama test, the Harmony test or the Verifi test.

You can choose to have the NIPT test. You might have to pay a fee for it. If it's not available in your hospital, you can get the tests done privately.

NIPT involves a blood test and it's accurate when interpreted correctly. It's usually done between 10 to 12 weeks of pregnancy.

The test looks at very small bits of DNA:

• placental DNA
• your baby’s DNA

DNA is a person's unique genetic code. These pieces of DNA will be in your bloodstream by about 10 weeks of pregnancy.

Almost all the time these pieces of DNA are the same. But sometimes they are different. This is very rare.

If they are different or if the result is positive or 'high risk', you'll be offered a diagnostic test. This is to confirm the test result.

Your obstetrician or midwife will discuss this with you. They will answer any questions you have.

For more advice and information about NIPT, talk to your midwife or GP.

Eye screening tests for women with diabetes

If you were diagnosed with diabetes before pregnancy, you'll be advised to have eye screening in each trimester. This is to check for signs of eye problems caused by diabetes such as diabetic retinopathy.

Diabetic retinopathy means that the diabetes has started to affect the blood vessels in the back of the eye. This can cause serious eye problems.

Some women develop diabetes during their pregnancy. This is called gestational diabetes. Pregnant women with gestational diabetes do not usually need to have eye screening during their pregnancy.

During the test:

1. The screening team will check your eyesight.
2. They'll put drops in your eyes - these drops make your pupils bigger so it is easier to see the blood vessels at the back of your eyes (retina).
3. They'll then take digital photographs of your retinas.

You should not drive after screening as the eye drops can blur your vision.