What Is Genetic Screening?

Genetic screening is a process used to determine a child's risk of inheriting certain diseases or birth defects from his or her parents. Couples planning to have a baby might be concerned about illnesses that have occurred in family members. The best time to have genetic screening is before a pregnancy, but it can also be done at specific time points during a pregnancy.

There are several tests that look for different genetic disorders.

Who Should Have Genetic Screening?

Keep in mind that genetic testing is not done for every pregnancy. Some have an increased risk of having a child with a genetic condition. Here are some common reasons your healthcare provider may recommend genetic screening:

    
  • Mother or father has family members with inherited disorders
  • Mother is 35 years old or older when you deliver your baby
  • Previous child with a hereditary disease or birth defect
  • Previous stillbirths or several miscarriages
  • Abnormalities in the pregnancy, such as too much or too little serum alpha fetoprotein (AFP)
  • Conditions that your healthcare provider may screen for include:

        
  • Down syndrome
  • Cystic fibrosis—Caused by two defective genes, affecting the lungs and pancreas.
  • Tay-Sach's disease—A brain disorder, which is more common in people of Eastern European (Ashkenazi) Jewish descent, that causes early death.
  • Thalassemia—A type of anemia caused by abnormal red blood cells. The condition is more common in people from southeast Asia, China, and Mediterranean countries, such as Greece and Italy.
  • Hemophilia—A blood clotting disorder.
  • Sickle cell anemia—More common in African Americans of sub-Saharan origin, affecting the red blood cells.
  • Any possible genetic defect that may affect your child in the future, such as BRAC mutations that increase the risk of breast and ovarian cancers.
  • What Should I Know Before Having Genetic Screening?

    You should find out about the medical history of your family, including hereditary diseases in your mother's and father's families. If possible, ask your parents and your partner's parents about any abnormalities, disabilities, or intellectual disability in the family. Make a record of any of the following personal information:

        
  • Miscarriages
  • Exposure to environmental hazards before or during pregnancy (such as x-rays or other radiation; chemicals used at work, home, or with hobbies)
  • Any prescription or nonprescription drugs you took before pregnancy or before you knew you were pregnant
  • Any history of alcohol or drug use
  • What Takes Place During the Genetic Screening Process?

    During the genetic screening process, your healthcare provider will ask you and your partner for a detailed family history of diseases, disorders, and birth defects. You may be given blood tests. If you are already pregnant, you might be given tests to examine the chromosomes and condition of the fetus. Examples of genetic screening tests given during pregnancy include:

        
  • Blood tests to check the levels of alpha fetoprotein, with possible follow-up tests to look for neural tube defects
  • Ultrasound scans to check for birth defects of the brain, heart, spine, arms, legs, and other organs
  • Chorionic villus sampling (CVS) to check for chromosomal abnormalities
  • Amniocentesis to check for chromosomal abnormalities
  • After the screening and tests, your healthcare provider will discuss the results with you and make recommendations about any treatment that may be beneficial. Treatment is a personal choice that is left entirely up to you. Your healthcare provider should provide you with lots of information about treatment options so that you can make informed choices.