Antenatal screening

SASH Maternity Services will offer you a number of screening and diagnostic tests during your pregnancy. Your midwife will advise you which tests are offered and why. These tests can help you find out about your own health and the health of your baby before birth.

All of the tests are optional – it’s your choice whether to have the test or not. The information these tests can provide will help you make choices about your pregnancy, and help your midwife provide the best care possible during your pregnancy and the birth.

The diagram below explains what tests will be performed, and at which stage of the pregnancy:

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You may want to ask some or all of these questions before deciding whether to have a test:

  • 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 the test shows there might be a problem?
  • What happens if I chose not to have the test?


Your midwife will give you a copy of the booklet Screening Tests for You and Your Baby (available to download below). This booklet explains all the tests you will be offered for you and your baby. It is available in different formats and languages.

Blood tests

We offer all pregnant women blood tests in the early stages of pregnancy to check for a number of problems. We recommend these blood tests are taken before 10 weeks of pregnancy. Your haemoglobin is checked for signs of anaemia (low iron levels) and your blood group and rhesus factor. We would also recommend screening for the following:

  • Infections diseases

    All women are offered screening for hepatitis B, HIV and syphilis, all these infections can cause serious harm to your baby and without a test you might not know you are infected. If an infection is found you will be offered specialist care to ensure you and your baby has the correct treatment.

    We offer screening for rubella susceptibility (German measles) to identify those women who are not protected against rubella. If you are found not to be protected we will offer you a vaccination after the birth of your baby before you leave the hospital. You will also be encouraged to have a further vaccination with your GP at around 3 months later. This will help protect you in future pregnancies.

  • Screening for Sickle Cell and Thalassaemia

    These are inherited disorders of the red blood cells. Anyone can carry a gene for one of these conditions but they are more common in people whose ancestors or blood relatives come from certain parts of the world. At booking your midwife will routinely ask you and the father of your baby where your families originated from. If your family origin is one from a high risk area you will be offered haemoglobinopathy screening. If you are found to carry an unusual haemoglobin gene we will discuss this with you, and will offer your baby’s father the same test to see if he carries a similar gene.

  • Combined screening test/quadruple screening test

    These tests assess the likelihood or chance that your baby has Down’s syndrome and two other rare chromosomes problems known as Edward’s and Patau’s syndromes. Once you know what your chance is you can then decide whether you want to know for sure by having a diagnostic test. The screening test you will be offered will depend on how many weeks pregnant you are.

    Combined screening test

    SASH offers the combined screening test between 11 weeks and 2 days up to 14 weeks and 1 day of pregnancy. This test involves an extra measurement of the fluid on your baby’s neck (known as the nuchal translucency or NT) at the dating scan. We will then take a blood test from you immediately after the scan. The results are normally available within 2 working days following the sample of blood being taken and sent to our laboratory.

    Quadruple or Quad test

    This screening test is only available if your pregnancy is too advanced for the combined screening test. It requires a blood test to be taken from you anytime from 14 weeks 2 days up to 20 weeks. The results are normally available within 2 working days following the sample of blood being taken and sent to our laboratory.

    Please note: After 20 weeks of pregnancy your options for screening are limited and you would need to discuss this with one of our antenatal screening midwives on: 01737 768511 Ext 6977.

    Or their E-mail:

    The midwives are available Monday to Friday 8am to 5pm

  • Diagnostic tests (also known as invasive tests)

    These tests will give you definite information about your baby’s chromosomes and confirm whether or not your baby has a chromosomal abnormality. All women who are assessed as being high risk as a result of either the combined or quadruple screening test will be offered a diagnostic test. Those women who have previously had a pregnancy affected by a chromosome problem or have a history of an inherited condition will also be offered a diagnostic test. It is important to know that a diagnostic test carries a risk of miscarriage of 1 in 100, so you need to think carefully before deciding to have the test.

    All women who accept a diagnostic test will be referred to our tertiary centre at St George’s Hospital Fetal Medicine Unit.

    There are 2 different diagnostic tests:

    Chorionic Villus Sampling (CVS) and Amniocentesis

    Both tests are done under ultrasound guidance and a local anaesthetic and using a fine needle a small amount of either placental tissue (CVS) or amniotic fluid (amniocentesis) are extracted and sent to the laboratory for testing. The results take between 4 to 7 working days to come back. St George’s hospital will speak directly to you with the result.

    It is important it remember that no test or scan can rule out all problems in your baby. It is not always possible to detect some rare chromosome problems and genetic disorders even with a diagnostic test.

    What happens if a problem is diagnosed?

    Most babies, even those with an increased risk following antenatal screening will have normal chromosomes. For those cases where we detect an actual problem a member of the antenatal screening  team will be in touch and will tell you what the problem and is and how it may affect your baby. You will be invited to meet with a member of the screening team and a fetal medicine consultant so we can discuss what options are available to you.

  • Physical abnormalities (mid-pregnancy scan)

    This is the mid pregnancy scan which usually takes place between 18 weeks and 20 weeks 6 days of pregnancy. The scan looks for physical abnormalities in the baby. It does not find everything that might be wrong. The scan looks in detail at your baby’s bones, heart, brain, spinal cord, face, kidneys and abdomen. The scan picks up around 50% of heart defects and around 90% of babies with Spina bifida.

    If a problem is detected you will be referred to one of our fetal medicine consultants or to St George’s Hospital Fetal Medicine unit for further investigation or treatment. For more information about the main conditions that are looked for during the mid-pregnancy scan please see:


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Useful resources

Download the Screening Tests for You and Your Baby leaflet

To download this leaflet in other languages, please visit the UK National Screening Committee website.

Download the information leaflet about polyhydraminos Download the Antenatal and Newborn Screening Timeline sheet
Antenatal results and choices logoAntenatal Results and Choices website
Down's syndrome association logoDown’s Syndrome Association
SOFT logoSOFT (Support Organisation for Trisomy 13 & 18)


For newborn screening information, please visit the newborn screening page>>