Blood tests

A sample of your blood, when analysed by a laboratory can provide your doctor with all sorts of vital information.

Early in pregnancy, your blood will be tested for some or all of the following: blood group; anaemia (shortage of red cells); Hepatitis B; rubella (German measles) to ascertain whether you are immune to the disease or not; whether you are Rhesus negative or positive. If you are concerned about some of these tests, ask your doctor to explain what he or she is testing for and why.

Blood tests can also detect serious diseases. At about 16 weeks, a blood test can show whether the level of AFP (alpha-fetoprotein - a substance which crosses from the baby into the mother's blood) is unusually high, which can indicate that the baby has a serious problem, such as spina bifida (abnormality of the spine) or anencephaly, where there is no brain or skull.

The test is not foolproof and, before jumping to conclusions, your doctor will suggest further investigation - possibly ultrasound and/or amniocentesis. A high level of AFP can be due, for example, to a multiple pregnancy.

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