Genetic tests are done by analyzing small samples of blood or body tissues. They determine whether your baby carry genes for certain inherited disorders.
Genetic testing has developed enough so that doctors can pinpoint missing or defective genes. The type of genetic test needed to make a specific diagnosis depends on the particular illness that a doctor suspects.
Many different types of body fluids and tissues can be used in genetic testing. For deoxyribonucleic acid (DNA) screening, only a very tiny bit of blood, skin, bone, or other tissue is needed.
Genetic Testing During Pregnancy
For genetic testing before birth, pregnant women usually undergo amniocentesis or chorionic villus sampling.
Amniocentesis is a test performed between weeks 16 and 18 week of a woman's pregnancy. The doctor inserts a hollow needle into the woman's abdomen to remove a small amount of amniotic fluid from around the developing fetus. This fluid can be tested to check for genetic problems and to determine the sex of the child. When there's risk of cesarean section or premature birth, amniocentesis may also be done to see how far the child's lungs have matured. Amniocentesis carries a slight risk of inducing a miscarriage.
Chorionic villus sampling (CVS) is usually performed between the 10th and 12th weeks of pregnancy.See other explanation.
Doctors recommend genetictesting for any of the following reasons:
•A couple is planning to start a family and one of them or a close relative has an inherited illness. Some people are carriers of genetic illnesses, even though they don't show, or manifest, the illness themselves. This happens because some genetic illnesses are recessive — meaning that they're only expressed if a person inherits two of the problem gene, one from each parent. People who inherit one problem gene from one parent but a normal gene from the other parent won't have symptoms of a recessive illness but will have a 50% chance of passing the problem gene on to their children.
•An individual already has one child with a severe birth defect. Not all children who have birth defects have genetic problems. Sometimes, birth defects are caused by exposure to a toxin (poison), infection, or physical trauma before birth. Even if a child does have a genetic problem, there's always a chance that it wasn't inherited and that it happened because of some spontaneous error in the child's cells, not the parents' cells.
•A woman has had two or more miscarriages. Severe chromosome problems in the fetus can sometimes lead to a spontaneous miscarriage. Several miscarriages may point to a genetic problem.
•A woman has delivered a stillborn child with physical signs of a genetic illness. Many serious genetic illnesses cause specific physical abnormalities that give an affected child a very distinctive appearance.
•A woman is pregnant and over age 34. Chances of having a child with a chromosomal problem (such as trisomy) increase dramatically when a pregnant woman is older. Older fathers are at risk to have children with new dominant genetic mutations, those that are caused by a single genetic defect that hasn't run in the family before.
•A child has medical problems that might be genetic. When a child has medical problems involving more than one body system, genetic testing may be recommended to identify the cause and make a diagnosis.
•A child has medical problems that are recognized as a specific genetic syndrome. Genetic testing is performed to confirm the diagnosis. In some cases, it also may aid in identifying the specific type or severity of a genetic illness, which can help identify the most appropriate treatment
My personl experience: Even if you are not in one of these groups its your choice to do these test...I personally felt much better after knowing everyting was fine. It gives you more time to prepare yourself to whatever happens.