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Blood Tests

Why are these done?

As an important part of your care during pregnancy there are a number of blood tests offered. These tests are performed to help protect your health and the health of your baby. The tests can all usually be done from one blood sample which is usually taken at around 16 weeks. The blood sample taken is put into several tubes for the different tests.

A blood test is also offered to women to screen for an increased risk of defects of the backbone for example, Spina Bifida and also Down's syndrome. You do not have to have this test if you do not want to.

What am I tested for?

Full Blood Count

This measures your haemoglobin, which is a way of assessing the level of iron in your blood. If this is low it indicates you could be anaemic and you may be offered iron tablets or other appropriate treatments. If any other problems are identified further tests will be carried out if required.

Blood Group

This test tells us several things about your blood. Firstly, it shows which main blood group you belong to (A, B, O or AB). It also shows whether there are any blood group antibodies in your blood. This could be a result of a previous transfusion or pregnancy.

Another finding is whether you belong to the Rhesus positive or Rhesus negative blood group.

If you are Rhesus positive?

No further action is necessary.

If you are Rhesus negative?

You are likely to require injections of a treatment called 'anti-D' at different times during pregnancy (for instance, if you have some bleeding) and once after delivery. This helps prevent any complications with future babies you may have. (One in six women are found to be Rhesus negative).

Rubella (German Measles)

Most women are now protected from rubella infection having been immunised in childhood. If you have a satisfactory level of immunity, you and your baby should be protected if you come into contact with someone who has rubella during your pregnancy.

However, if the test shows that you are not immune or have low levels of immunity, you will be given health advice and offered immunisation after delivery. Rubella infection in the first 20 weeks of pregnancy can be harmful to your baby and may affect your baby's development leading, for example, to deafness. If you develop a rash or have possible contact you should contact your doctor or midwive.


This infection acquired through sex is now rare, but we test for it anyway because without treatment syphilis can damage your health and that of your baby by causing developmental difficulties. If the test is positive we can offer effective treatment and prevent the infection affecting your baby by prescribing a course of antibiotics.

Hepatitis B

Hepatitis B can be passed on from mother to baby during birth. It is a virus which infects the liver. It can be carried in the blood for many years before causing any sign of illness. Without a test, you may not know if you are infected. If the Hepatitis test is positive, specialist help will be provided for you and your baby.

An immunisation programme started at birth can usually prevent infection in babies born to infected mothers enabling them to have a healthy life. Without immunisation, many babies born to mothers who are hepatitis B carriers, become infected.

These babies are at risk of developing serious liver disease as they grow older.

Human Immunodeficiency Virus (HIV)

The Human Immunodeficiency Virus (HIV) is the virus that causes AIDS (Acquired Immunodeficiency Syndrome).

Infected pregnant women can pass HIV to their babies during pregnancy, childbirth and also through breastfeeding. HIV attacks the immune system and destroys the body's defences against infection and disease. It can take years for HIV to do enough damage for someone to become ill and many will be unaware that they are infected unless they have a test.

If your HIV result is positive, advice and treatment under the guidance of specialists will be offered. This will include giving you and your baby medications against the virus and advice about the best type of delivery and method of feeding your baby. This can greatly reduce infection being passed on to your baby.

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Are there any risks associated with these tests?

There are no associated risks for your baby with these types of tests.

When will I get the results?

You will be informed of the results of routine tests (such as your iron levels) at your next clinic visit. If any serious problem is found, or there is something you should know, you will be contacted immediately.

Some of these tests are routinely repeated later in pregnancy. From time to time technical problems can occur with the analysis of blood and a repeat sample may be requested.

Having a blood test in itself has no implications for current or future life insurance policies. However, any positive result for infection may need to be declared on insurance health questionnaires and could have insurance implications. You may wish to check your own policy for further details.

The results will help us identify any potential problems with your pregnancy. However, you should be aware that a blood test alone cannot detect all cases certain abnormalities, for example, Spina Bifida and Down's syndrome.

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Could my baby still be normal?

Yes. The majority of women who are recalled go on to deliver perfectly healthy babies.

How can I get more information?

Further information about the tests taken during your pregnancy can be obtained from:

Positively Women
Tel: 020 7713 0444
Link opens in new windowwww.positivelywomen.org.uk

FPA Scotland (Family Planning Association)
Tel: 0141 576 5088
Link opens in new windowwww.fpa.org.uk

Waverley Care
Tel: 0131 661 0982
Link opens in new windowwww.waverleycare.org

The Sandyford Initiative
Tel: 0141 211 8600
Link opens in new windowwww.show.scot.nhs.uk

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