National Society of Genetic Counselors

    Five Things I Tell My Patients Considering Prenatal Genetic Testing

    The joy that prenatal genetic testing has brought to gender reveal parties is undeniable: specialty cakes, powder-filled baseballs, a box full of pink or blue balloons. But that’s just one of several results you can get from prenatal testing. As a genetic counselor, I’ve also witnessed the anxiety that genetic testing can generate during pregnancy. For instance, a pregnant woman was told her baby is likely to be born with a genetic condition, only to give birth to a baby without the condition. Or another woman finds out her baby has a genetic condition, but how severe it will be is impossible to predict before delivery.

    Technological advances that allow us to check on a baby’s development during pregnancy have expanded dramatically and include ultrasounds, blood tests, and diagnostic procedures. These tests are offered to all pregnant women to evaluate conditions that can happen by chance, even when there is no family history. The wide array of testing options often eases expectant parents’ worries but can also cause anxiety. Obtaining more information about testing can help you decide which test, if any, is right for you and your pregnancy.

    In my role as a genetic counselor, I help expectant parents understand the benefits, risks, and limitations of prenatal genetic testing. To begin the process, I like to discuss the following five things with them:

    1. Not all genetic tests are the same. There are individual tests for a variety of different conditions, such as Down syndrome, cystic fibrosis or spina bifida. It’s important to discuss with your healthcare provider which conditions you are comfortable testing for and which ones you prefer to skip. There are also different methods of testing. A healthcare provider can explain the differences between how these tests are performed and what they might find.

    2. Genetic testing is optional. National organizations recommend that all pregnant women are offered genetic testing but it’s up to you to decide whether testing is right for you. There are several questions to ask yourself before having a prenatal genetic test, but the most important include:
      • Would learning your baby has a health concern or genetic condition during the pregnancy be helpful or detrimental to you? Most genetic conditions don’t have a cure or treatment so knowing about it before you give birth may not help improve the outcome after birth. Even so, some families prefer to learn of a condition before birth.
      • Do you know the risks of prenatal genetic testing and are you willing to accept them? Many genetic tests are blood tests and they carry no risks for complications such as miscarriage. But blood tests aren’t 100 percent accurate or conclusive, and inconclusive results may require more testing.  Sometimes a follow-up test is an invasive procedure, such as amniocentesis, which does carry a risk for pregnancy complications. Also, while most test results are accurate, they sometimes can cause expectant parents anxiety and stress. 

    3. There is no way to rule out all genetic conditions. Genetic testing technology has made major advances. You may see blood tests that boast greater than 99 percent accuracy, but no blood test can rule out a condition with 100 percent certainty. There are thousands of genetic conditions, and while most are extraordinarily rare, there is no test that evaluates for all of them. In fact, many blood tests only evaluate for a few genetic conditions.

    4. Some genetic tests can be performed before you are pregnant. Many genetic conditions are not inherited but happen by chance at conception so there’s no way to test for them before pregnancy. On the other hand, there are conditions that a perfectly healthy person may silently carry and pass on to a baby. For many of these conditions, there’s no risk to the baby unless both parents carry the same condition. These are called autosomal recessive conditions and include disorders such as cystic fibrosis, spinal muscular atrophy and sickle cell anemia. Testing couples for these types of conditions can be done at any time, ideally before becoming pregnant. If one parent is found to carry a condition, testing their partner is recommended.

    5. There is no right or wrong choice. The decision to undergo testing is completely yours. Some women say they feel an obligation to have a test because it was offered or because their doctor told them to, but a testing decision should be based on your desires, needs, and values. Some women want to know as much as possible as early as possible, while others feel the information is unnecessary or unhelpful.


    Remember, most babies are born perfectly healthy. But these questions and considerations are important if you do have any concerns or are considering prenatal genetic testing. Genetic counselors can help you through the decision-making process. Find a genetic counselor in your area at www.findageneticcounselor.com.

     

    Blair Stevens, MS, CGC, is a prenatal expert for the National Society of Genetic Counselors. She sees patients at the Fetal Center at Children’s Memorial Hermann, where she helps families understand diagnoses such as spina bifida, congenital diaphragmatic hernia and cleft lip and palate and their possible genetic associations.

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