Screening and tests

Early in your pregnancy you should be offered a number of tests.

Your doctor or midwife should tell you more about the purpose of any test you are offered. You do not have to have a particular test if you do not want it. However, the information these tests can provide may help your antenatal care team to provide the best care possible during your pregnancy and the birth. The test results may also help you to make choices during pregnancy.

Questions to ask your healthcare team

  • What is the test for?

  • What does the test involve?

  • Are there any risks?

  • What will the results show?

  • How and when will I get the results?

  • Who do I contact if I don't get the results?

  • What happens if I choose not to have the test?

  • What happens if the test shows that there might be a problem?

Ultrasound scans

You should be offered an ultrasound scan between 10 weeks 0 days and 13 weeks 6 days to estimate when your baby is due and to check whether you are expecting more than 1 baby. This scan may also be part of a screening test for Down's syndrome.

You should be offered another scan, normally between 18 weeks 0 days and 20 weeks 6 days, to check for physical problems in your baby. This is called the anomaly scan. Your doctor or midwife will give you more information about the scan and what the results may mean for you so you can decide whether you want to have the scan or not. If the scan shows a possible problem, you will be referred to a specialist to discuss the options available to you. It is important to realise that no test is 100% accurate.

Screening tests for Down's syndrome

Down's syndrome is a condition caused by the presence of an extra chromosome in a baby's cells. It occurs by chance at conception and is irreversible.

Early in your pregnancy you should be offered information and screening tests to check whether your baby is likely to have Down's syndrome. Your midwife or doctor should tell you more about Down's syndrome, the screening tests you are being offered, what the results may mean for you and the decisions that you may need to think about. You have the right to choose whether to have all, some or none of these tests. You can opt out of the screening process at any time if you wish. Screening tests will only indicate that a baby may have Down's syndrome. If the screening test results are positive, you should be offered further information, support and more tests to confirm whether or not your baby has Down's syndrome.

Between 11 weeks 0 days and 13 weeks 6 days, the screening test for Down's syndrome should be the combined test (an ultrasound scan and blood test). Between 15 weeks 0 days and 20 weeks 0 days, the screening test should be the triple or quadruple test (both are blood tests).

Blood tests

Anaemia

You should be offered 2 tests for anaemia: one at your booking appointment and another at 28 weeks. Anaemia is often caused by a lack of iron. If you develop anaemia while you are pregnant, it is usually because you do not have enough iron to meet your baby's need for it in addition to your own; you may be offered further blood tests. You should be offered an iron supplement, if appropriate.

Blood group and rhesus D status

Early in your pregnancy you should be offered tests to find out your blood group and your rhesus D (RhD) status. Your midwife or doctor should tell you more about them and what they are for. If you are RhD‑negative, you should be offered an anti‑D injection to prevent future babies developing problems.

Early in your pregnancy, and again at 28 weeks, you should be offered tests to check for red‑cell antibodies. If the levels of these antibodies are significant, you should be offered a referral to a specialist centre for more investigation and advice on managing the rest of your pregnancy.

Inherited blood conditions

Inherited blood conditions, such as thalassaemia and sickle cell disease, mainly affect people whose family origin is African, Caribbean, Middle Eastern, Asian or Mediterranean, but these conditions are also found in the North European population. At your first appointment, your midwife or doctor should give you information about inherited blood conditions, offer advice and support, and ask some questions about your and your partner's family origins to find out whether you are at risk of being a carrier or having a baby with an inherited blood condition. If you are a carrier of an inherited blood condition, the father of your baby should also be offered advice, support and screening without delay.

Testing for infections

Your midwife or doctor should offer you a number of tests, as a matter of routine, to check for certain infections. These infections are not common, but they can cause problems if they are not detected and treated.

Asymptomatic bacteriuria

Asymptomatic bacteriuria is a bladder infection that has no symptoms. Identifying and treating it can reduce the risk of developing a kidney infection. It can be detected by testing a urine sample.

Chlamydia

Chlamydia is a sexually transmitted vaginal infection that is more common in women who are younger than 25 years. It may have no symptoms but, rarely, may cause problems such as eye infections and pneumonia in the baby. The National Chlamydia Screening Programme has been set up to screen young women. If you are younger than 25, your midwife or doctor should give you more information about this at the booking appointment.

Hepatitis B virus

Hepatitis B virus is a potentially serious infection that can affect the liver. Many people have no symptoms. It can be passed from a mother to her baby (through blood or body fluids), but may be prevented if the baby is vaccinated at birth. The infection can be detected in the mother's blood.

HIV

HIV usually causes no symptoms at first but can lead to AIDS. HIV can be passed from a mother to her baby, but this risk can be greatly reduced if the mother is diagnosed before the birth. The infection can be detected through a blood test. If you are pregnant and are diagnosed with HIV, you should receive specialist care.

German measles (rubella)

Screening for German measles (rubella) is offered so that, if you are not immune, you can choose to be vaccinated after you have given birth. This should usually protect you and future pregnancies. Testing you for rubella in pregnancy does not aim to identify it in the baby you are carrying.

Syphilis

Syphilis is rare in the UK. It is a sexually transmitted infection that can also be passed from a mother to her baby. Mothers and babies can be successfully treated if it is detected and treated early. A person with syphilis may show no symptoms for many years. A positive test result does not always mean you have syphilis, but your healthcare team should have clear procedures for managing your care if you test positive.

Screening for medical conditions

Gestational diabetes

Gestational diabetes is a type of diabetes that develops in the later stages of pregnancy. Some women are more likely to develop gestational diabetes. You should be given information about gestational diabetes and offered a test if:

  • you are overweight (body mass index above 30 kg/m2)

  • you have given birth to a very large baby before

  • you have had gestational diabetes before

  • you have a parent, brother or sister with diabetes

  • your family origin is South Asian, black Caribbean or Middle Eastern.

Gestational diabetes usually improves with changes to diet and exercise. Tablets or insulin therapy may be needed to control diabetes if lifestyle changes do not work. Women with gestational diabetes may have more monitoring and interventions during both their pregnancy and their labour. If you are at risk of gestational diabetes and it is not detected and controlled, this may lead to a larger than normal baby which may mean a small risk of difficulties during the birth. NICE has produced information for the public on diabetes in pregnancy (see Other NICE guidance).

Pre‑eclampsia

Pre‑eclampsia is a condition that happens in the second half of pregnancy and can cause serious problems for you and your baby if it is not detected and managed. Signs of pre‑eclampsia are high blood pressure, protein in the urine and/or swelling of the hands, feet, ankles and sometimes face. Your blood pressure and urine will be checked for signs of pre‑eclampsia at every antenatal appointment.

Your risk of pre‑eclampsia should be assessed at your booking appointment in order to plan for the rest of your appointments. You are more likely to develop pre‑eclampsia when you are pregnant if you have any of these risk factors:

  • you are 40 or older

  • you have not had a baby before

  • your last pregnancy was more than 10 years ago

  • you or a family member has had pre‑eclampsia before

  • your body mass index is 35 kg/m2 or more (very obese)

  • you already have circulation problems such as high blood pressure

  • you already have kidney disease

  • you are expecting more than 1 baby.

You may need to have your blood pressure measured more often if you have any signs of pre‑eclampsia, such as protein in your urine or high blood pressure.

You should seek immediate medical help if you experience any symptoms of pre‑eclampsia, which include:

  • severe headache

  • problems with vision, such as blurred vision or lights flashing before the eyes

  • severe pain just below the ribs

  • vomiting

  • sudden swelling of the face, hands or feet.

Placenta praevia (low‑lying placenta)

Placenta praevia is when the placenta is low lying in the womb and covers all or part of the entrance (the cervix). In most women, as the womb grows upwards, the placenta moves with it so that it is in a normal position before birth and does not cause a problem.

If an earlier ultrasound scan (usually between 18 weeks 0 days and 20 weeks 6 days) showed that your placenta extends over the cervix, you should be offered another abdominal scan at 32 weeks. If this second abdominal scan is unclear, you should be offered a vaginal scan.