Protecting you and your baby

Every woman wants to remain healthy during her pregnancy and give birth to a healthy baby. Antenatal blood tests are designed to protect your health and the health of your baby and family/whanau by identifying conditions or diseases as soon as possible in your pregnancy so that treatment can be offered.

The tests

Six different tests are recommended routinely when you are first pregnant. These are usually carried out on the same sample of blood taken from you. The tests are:

• blood group and antibodies
• full blood count
• hepatitis B
• HIV
• rubella
• syphilis.

ABO blood group test

Your blood group can be A, B, O or AB. Your blood is checked for your group and for the presence of antibodies (part of your immune system). Certain antibodies can be harmful for your baby during pregnancy. If you are found to have antibodies that could affect your baby, monitoring and treatment to protect your baby are recommended.

Rhesus blood group test

This is another immune system test, for rhesus factor (mainly Rh D). Your blood group either has or does not have this factor present, so you are either Rh positive (Rh+) or Rh negative (Rh–). If you are Rh– and your blood mixes with your baby’s blood you can make antibodies which can cause severe anaemia and jaundice in this or your next baby.

Your blood can only mix with the baby’s if you have an antenatal bleed, miscarriage or abortion or during your birth. An injection of ‘anti-D’ after any of these things happen can prevent your body from making these potentially harmful antibodies.

Full blood count

This blood test checks whether your body has enough iron to manage the extra requirements of pregnancy. If your iron levels are low, you will feel more tired and will be less able to manage the loss of blood that occurs during birth. You will be offered advice about how to increase the iron in your diet and/or iron tablets. The full blood count also checks your platelet levels. Platelets help your blood to clot.

Rubella (German measles)

This test checks that you are immune to (protected against) rubella, also known as German measles. If you catch the rubella virus in pregnancy it can lead to severe problems for your baby (eg, deafness or brain injury) or miscarriage.

If you are not immune, you can have a vaccination to prevent problems in future pregnancies. This vaccination can only be given when you are not pregnant. It is best carried out soon after you have given birth or following a miscarriage or termination of pregnancy.

Hepatitis B

Hepatitis B is a virus that can be passed to a baby during birth. You may have this disease but not know because there are often no symptoms. It can also be passed on to your family/whanau through contact with infected blood.

Hepatitis B can cause significant health problems, including liver damage. About 20% of babies exposed to hepatitis B during birth, and left untreated, become infected. Over 90% of untreated babies become carriers of the virus.

If your lead maternity carer (LMC) knows you have hepatitis B they can offer your baby immunoglobulin and vaccination at birth to help prevent your baby becoming infected. Your LMC can provide further information about hepatitis B, or visit the Hepatitis Foundation website www.hepfoundation.org.nz.

HIV

Human immunodeficiency virus (HIV) affects your body’s ability to fight infection and can cause AIDS. HIV is passed on to others by contact with blood or body fluids. If you have HIV, it can be passed on to your baby during pregnancy, birth or breastfeeding.

Tests are now offered to pregnant women because the risk of baby becoming infected can be reduced from between 25% and 31.5%, to less than 1% if you are diagnosed and treated during pregnancy, do not breastfeed your baby and your baby is treated with medicine in the first six weeks of life. New medicines not only protect your baby but can also make a big difference to your health, helping you to stay well for yourself and your family/whanau.

In 1 in 1000 tests, the woman will need to have a second blood test to confirm her HIV test is negative. This is because this test is so sensitive it occasionally picks up some antibodies that are not HIV. In most of these cases, the second blood test will show the woman does not have HIV.

For more information, visit the National Screening Unit website: www.nsu.govt.nz, the NZ AIDS Foundation website: www.nzaf.org.nz or www.positivewomen.org.nz.

Syphilis

Syphilis is a rare infection in New Zealand, but it is becoming more common. If left untreated, it can cause serious health problems for you and your unborn baby.

Like HIV, it can be passed on either sexually or from mother to baby during pregnancy. Most women with syphilis do not know they have the disease because they feel well and have no symptoms. A blood test in early pregnancy, and then early treatment if needed, can help to avoid these problems.

Your results

Your results will be available from the health professional who organised your blood tests.

Confidentiality

All test results are confidential. If you need any support, information or treatment you will be referred to the appropriate healthcare professional and receive care that is professional, respectful and confidential.

Further information

If you would like more information about these or other screening tests/programmes, or need to have information in a different language, please ask your midwife, GP or specialist or visit the National Screening Unit website: www.nsu.govt.nz.

This information has been adapted from a leaflet produced by the Waikato District Health Board. The information has been reviewed and approved by the Ministry of Health, New Zealand College of Midwives, Royal Australian and New Zealand College of Obstetricians and Gynaecologists (NZ Committee) and the Royal New Zealand College of General Practitioners. Last reviewed September 2011.