Genetic screening is an optional test offered during pregnancy. Find out if these tests are necessary for you and your baby-to-be.

Your provider may recommend that you be screened through blood tests to determine whether you're a carrier for a particular genetic disorder, depending on your racial background and family history. Genetic screening tests are optional, and the decision to have them is yours. You may decline the screening. Or you may agree to the tests so that you can be as informed as possible about the potential effects of genetics on your unborn baby's health. If you and your partner should discover that you carry genes that put your child at greater risk for a potentially life-threatening disease, your provider will likely advise you to have a genetic test such as chorionic villus sampling (CVS) or amniocentesis to find out if your baby has the illness. This will help prepare you ahead of time to either offer your child the best medical help available or terminate the pregnancy. The most common of these inherited disorders include:

  • Tay-Sachs disease, Canavan disease, and familial dysautonomia. If you are of Eastern European Jewish (Ashkenazi) descent, the American College of Obstetricians and Gynecologists recommends that your health care provider offer carrier screening for Tay-Sachs disease, Canavan disease, and familial dysautonomia. All of these diseases affect a baby's central nervous system, are incurable, and may be associated with a shortened life span.
  • Cystic fibrosis (CF). This disease most commonly affects breathing and digestion. Individuals with CF are born with an abnormal protein that prevents chloride from passing normally in and out of certain cells, including cells lining the lungs and pancreas. As a result, these cells produce a thick, sticky mucus and other secretions, making it difficult to breathe, causing frequent lung infections, and harming digestion. About 1 in 30 Caucasians is a carrier of CF. Although it is more common in Caucasians, all racial groups are affected by this disease.
    CF is usually treated through special diets, medications that contain pancreatic enzymes to aid digestion, daily respiratory therapy, and mucus-thinning medications. Depending on the severity of the disease, individuals with CF may die in childhood or live past their 40s.
  • Thalassemia. This describes a group of blood diseases, most of which are different forms of anemia (a deficiency of red blood cells). Your health care provider may test for this if your routine blood work indicates that thalassemia is a possibility. The two main types are alpha and beta thalassemias, named according to which part of hemoglobin (a protein that carries oxygen) is lacking.
    Some forms of thalassemia are more severe than others. It can occur worldwide but is more common in people of Greek, Italian, Middle Eastern, African, or Asian descent. Some children with thalassemia appear healthy until early childhood, when they grow slowly and appear listless; others may die in utero. Children with thalassemia major, a severe form of the disease, may need to have blood transfusions and antibiotics for life.
  • Sickle-cell anemia. This is a disease caused by abnormal hemoglobin, the red blood cell protein that carries oxygen from the lungs to other parts of the body. There are several types of sickle-cell anemia, depending on which genes a child inherits from his parents. Some people affected by sickle-cell anemia lead normal lives, while others suffer severe complications. Infants and young children with sickle-cell anemia are more prone to serious bacterial infections. Individuals with sickle-cell anemia may also suffer from pain crises, stroke, vision problems, slow growth, and acute chest syndrome (similar to pneumonia). Sickle-cell anemia affects mostly African-Americans; approximately 1 in 12 is a carrier. It is much less common in other racial groups.
    Children affected with sickle-cell anemia may be treated with antibiotics to prevent infection. Other symptoms of the disease are treated as they arise; for instance, there are now medications used to treat painful episodes, and individuals at an increased risk of stroke may have regular blood transfusions to decrease the risk.

Originally published in You & Your Baby: Pregnancy.

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