Prenatal Genetic Testing What is Prenatal Genetic Testing? More than 95% of all newborns are born without birth defects, however, approximately 3-5% of infants will be born with some type of birth defect, and many of these birth defects are caused by genetic disorders. Examples of genetic disorders are trisomy 21 (Down’s Syndrome), cystic fibrosis, and sickle cell disease. Prenatal genetic testing refers to tests offered during pregnancy to look for these and other genetic disorders. There are two types of genetic tests. 1) Screening tests help expectant parents understand if they are at low risk or high risk for having an infant with a genetic disorder. They do not give a yes or no answer – they provide an estimate of whether a disorder may be present. These tests create no risk to the pregnancy. Common screening tests include the Nuchal Translucency test for Down’s Syndrome and the Cystic Fibrosis carrier test. 2) Diagnostic tests are used to confirm whether or not a condition is present in an infant. Chorionic villus sampling and amniocentesis are diagnostic tests. Diagnostic tests do involve a risk of miscarriage. Will I have prenatal genetic testing? Testing for cystic fibrosis and trisomy (13, 18, 21) are offered to all of our patients in their first trimester. In addition, all patients are offered the AFP test at 16 weeks to help determine their risks for having a baby with spina bifida. Certain ethnic groups are at risk for other genetic disorders, and those patients will be offered additional testing. Your provider will talk with you about genetic testing at your first visit and will help you decide which tests are appropriate for you. Genetic testing is optional and there are several questions to consider when you are deciding if you want genetic testing.
- Do I want the information provided by genetic testing?
- Do I want to know about these birth defects before my baby is born?
- Will having this information help me make choices about my pregnancy?
- Will doing these tests make me feel less anxious about my pregnancy?