Birth defects tests are done during pregnancy to look for possible problems with the baby (fetus). Birth defects develop when something is wrong with the genetic material (genes or chromosomes), an organ, or body chemistry. A birth defect may have only a mild impact on a child's life, or it can have a major effect on quality of life or life span.

Birth defects include:

• Genetic disorders such as Down syndrome.
• Diseases passed in a family (inherited) such as Tay-Sachs, hemophilia, and cystic fibrosis.
• Structure problems such as heart defects and neural tube defects, including spina bifida.

Parents can choose whether to have a test for birth defects. If you choose to have a test, you may want to talk with a genetic counselor. The counselor can talk with you about the reasons to have or not have the test. He or she can also help you find other resources for support and decision-making.