Special tests

Your blood will have been tested at your booking-in appointment to determine your blood group and to establish its rhesus (Rh) status. The rhesus status of your blood depends on whether or not it possesses the rhesus factor. If the factor is present, your blood is Rh-positive, if it is absent, your blood is Rh-negative. Most people's blood is Rh-positive.

If both you and the baby's father are Rh-negative, there is not a problem. Complications only occur when the father's blood is Rh-positive and yours is Rh-negative. The unborn baby may acquire the rhesus factor from its father, which can result in its blood being incompatible with yours. This can lead to a serious or even fatal illness for the baby before, or after the birth. Fortunately, this rarely affects a first pregnancy and it can be prevented in subsequent pregnancies by injections of anti-D gamma globulin, an antibody that may be given during pregnancy and again within 72 hours of a baby being delivered.

SPECIAL TESTS

There are a number of ante-natal tests that are used in special circumstances and usually only when there is some fear of genetic abnormality. They include:

1. Amniocentesis
2. Chorionic villus sampling (CVS)
3. Cordocentesis
4. Triple/ double test