Maternal blood tests

Routine blood tests

Haemoglobin - to make sure you are not anaemic.

Blood grouping and Rhesus factor - to ensure maximum safety should you need a blood transfusion. It will also tell us if your baby needs to be protected from Rhesus disease.

Rubella - to check your immunity.

Syphilis - this is a rare disease but can affect your baby if not treated.

Random blood sugar - to identify mothers who are at risk of diabetes.

Special blood tests

These are available in certain circumstances. If you feel that you may be at risk from any of these conditions, please discuss with your doctor and/or midwife.

Hepatitis B screening (from April 2000)

Hepatitis is a virus infection which affects the liver and after a long time can cause liver failure. The liver is important for removing toxins from the body and making proteins for cells to grow. Many people carry the Hepatitis B virus without knowing it. This infection can occur silently and the virus can be transmitted sexually, or by contact with blood or other body fluids.

If a mother is found to have Hepatitis B her baby can be protected from the infection by a course of vaccinations soon after the birth. Mothers found to have Hepatitis B infection will be offered appropriate counselling and treatment. Please let the midwife know if you do not wish to have this test.

HIV- please discuss this with your midwife/obstetrician/GP.

Sickle Cell screening - for those of African and Caribbean origin.

Thalassaemia - for those of Mediterranean origin or with a family history of the disease.

Toxoplasmosir - see The Pregnancy Book or Bounty Pregnancy Guide.

Cystic fibrosis - if close family history.

Additional blood test (Triple Test)

This is an optional blood test at 15-20 weeks of pregnancy to aid the detection of Down's syndrome and spina bifida.

How does the screening test work?

The test measures the amounts of three substances called AFP (alpha fete protein), hCG (human chorionic gonadatrophin) and uE3 (unconjugated oestriol) in the mother's blood. In pregnancies at increased risk of Down's syndrome, the amounts of AFP and UE3 are reduced and the amount of hCG is increased.

What does the result mean?

The measurement of AFP, hCG and uE3 are used to calculate the risk of Down's syndrome. If the risk is low, no further action is required. If the risk is higher than one in 250, you will be offered an amniocentesis to test for Down's syndrome. (Since 1:250 is still a small risk in the great majority of cases the amniocentesis test will give a normal result.)

What about older mothers?

Older mothers are known to be at an increased risk for Down's syndrome and in the past women over the age of 35 years have been offered a specific test for Down's syndrome, usually amniocentesis. With a blood test, the risk of Down's syndrome is worked out from the measurement of AFP, hCG and uE3, taking into account the age of the mother. For many older mothers shown to be at low risk for Down's syndrome, further tests will nor be necessary.

What are the risk of amniocentesis?

Amniocentesis involves taking a sample of the fluid which surrounds the baby in the womb. The risk that this will cause a miscarriage is about one chance in 150. The amniocentesis test takes about three weeks to give a result. An information leaflet is available.

What about other types of abnormality?

The screening test can also show if there is an increased risk for some other abnormalities, particularly spina bifida which gives high levels of AFP. In this case we would advise a repeat of the blood test, and a careful look at the baby with the ultrasound scanner. If the results of these tests are satisfactory, no further action need be taken, but should doubt remain you would be offered amniocentesis so that further tests could be carried out.

What happens if an abnormality is found?

Information about the type of abnormality that has been found and how it may affect your baby will be given to you. If it is a serious abnormality you and your partner may decide to have the pregnancy terminated.

If the test gives a normal result, does it guarantee that the baby will be healthy?

No, because it cannot detect every abnormality, the screening test is not a total guarantee that the baby will be healthy. The test cannot absolutely exclude Down's syndrome, spina bifida or other abnormalities, but if the result is low risk it reduces the chances of something being wrong.

Do I have to have the blood test?

The test is entirely optional. In deciding whether or not to have the test you should think carefully about what you would do if the test shows an increased risk of Down's syndrome or other abnormality.

When do I hear the result of the blood test?

If the result shows an increased risk, you will be contacted by your community midwife. This is usually 7-10 days after having the test done. She will give you an appointment to discuss the results with an obstetrician. You will receive a letter within 10-14 days of having the test, if the result is normal.