Prenatal testing for genetic conditions

Many health concerns present at birth are due to genetic conditions. Genetic conditions are caused by changes in genes or threadlike pieces of DNA called chromosomes. The two main types of testing for genetic conditions during pregnancy are:

• Screening tests. Prenatal screening tests can find out whether your baby is more or less likely to have certain genetic conditions. Most often, these screening tests are offered during the first or second trimester of pregnancy. They include blood tests and ultrasound. Irregular results on a screening test don't mean that your baby has a genetic condition. Your healthcare professional can help you decide whether you should get diagnostic tests to find out for sure.
• Diagnostic tests. These tests are the only way to know whether your baby has a genetic condition. You can get a diagnostic test if a screening test finds that your baby has a higher risk of a genetic condition. Or you could think about getting a diagnostic test if your age, family history or health history raises your baby's risk of a genetic condition. Some diagnostic tests carry a slight risk of miscarriage. These tests include chorionic villus sampling and amniocentesis.