What Is Genetic Screening?Genetic screening is a process used to determine a child's riskof inheriting certain diseases or birth defects from his or herparents. Couples planning to have a baby might be concerned aboutillnesses that have occurred in family members. The besttime 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 yourbaby
- Previous child with a hereditary disease orbirth defect
- Previous stillbirths or several miscarriages
- Abnormalities in the pregnancy, such as too much or too little serumalpha fetoprotein (AFP)
- Down syndrome
- Cysticfibrosis—Caused by two defective genes, affecting the lungs and pancreas.
- Tay-Sach's disease—A braindisorder, 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 southeastAsia, 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'sfamilies. If possible, ask your parents and your partner's parentsabout any abnormalities, disabilities, or intellectual disability in thefamily. Make a record of any of the following personalinformation:
- Exposure to environmental hazards before or during pregnancy(such as x-rays or other radiation; chemicals used at work, home, or withhobbies)
- Any prescription or nonprescription drugs you took beforepregnancy 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 providerwill ask you and your partner for a detailed family history ofdiseases, disorders, and birth defects. You may be given bloodtests. If you are already pregnant, you might be given tests toexamine the chromosomes and condition of the fetus. Examples ofgenetic screening tests given during pregnancy include:
- Blood tests to check the levels of alpha fetoprotein, with possible follow-up tests to lookfor 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 chromosomalabnormalities
- Amniocentesis to check for chromosomal abnormalities
American Congress of Obstetricians and Gynecologists
Office on Women's Health
Society of Obstetricians and Gynaecologists of Canada
Women's Health Matters
Genetic counseling. American Pregnancy Association website. Available at: http://americanpregnancy.org/getting-pregnant/genetic-counseling. Updated March 2011. Accessed December 9, 2014.
Routine prenatal care. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated December 4, 2014. Accessed December 9, 2014.
Routine tests in pregnancy. American Congress of Obstetricians and Gynecologists website. Available at: http://www.acog.org/~/media/For%20Patients/faq133.pdf?dmc=1&ts=20121217T1134335563. Accessed December 9, 2014.
Screening for birth defects. American Congress of Obstetricians and Gynecologists website. Available at: http://www.acog.org/~/media/For%20Patients/faq165.pdf?dmc=1&ts=20121217T1134388121. Accessed December 9, 2014.
- Reviewer: Michael Woods, MD
- Review Date: 12/2014
- Update Date: 12/09/2014