May 17, 2024

If you’re pregnant or trying, your provider will likely offer a referral for genetic testing. Here’s what to know about this optional workup.

Pregnancy — and even pre-pregnancy — comes with a smattering of medical tests and physical exams. So when your OB/GYN offers you genetic testing and says it’s optional, you may be inclined to skip it. But not so fast. Genetic testing during pregnancy can be a useful — even lifesaving — tool to have on your side and can even help the whole family better understand its genetics. Here’s what to know.

What is genetic testing?

Genetic testing includes a wide range of services, but in this case, we’re talking specifically about prenatal genetic testing, which is testing during pregnancy or preconception. It’s conducted to determine how likely it is a baby will be born with a genetic disorder or birth defect, and it’s entirely optional.

“We’re always available to talk about the chances of having a genetic condition and the benefits and risks of genetic testing. That’s what we’re here for.”

“It’s never something that people should feel like they have to do,” says Emily Franciskato, a reproductive genetic counselor with Vanderbilt Women’s Health. “But if information is something that people feel like empowers them and any choices that they make, that’s what it’s for.”

Genetic testing comes in two types. Screening tests are less invasive and are often performed by testing mom’s blood or by ultrasound. These tests provide parents with a risk profile but can’t determine with certainty if a fetus has a particular disorder. Diagnostic tests, on the other hand, can provide definitive information, but the tests also tend to be more invasive and come with risk.

When to get genetic testing

Testing can be performed prior to becoming pregnant, during pregnancy or once baby is born. Each stage has specific tests available.

  • Pre-pregnancy. Most babies with genetic disorders are born to healthy parents. That’s because even healthy adults can be carriers of genetic abnormalities, and when both partners have the same genetic defects, their offspring are much more likely to have the disorder. Carrier screening is performed using blood samples from both partners. These tests determine the likelihood a baby will be born with a genetic disorder. Of course, all tests have their limitations, and no carrier screening or genetic test can guarantee a healthy pregnancy.
  • Pregnancy. Testing throughout pregnancy can provide additional information about the health of a fetus. Genetic screening with a blood test can be performed as early as the end of the first trimester. Midterm ultrasound (often referred to as an anatomy scan) performed between 18 and 20 weeks also provides information on certain genetic disorders and birth defects.

    If an abnormality is detected on one of these screenings or the parents just want to gather as much information as possible, they can then decide whether or not to participate in diagnostic testing. Having this information can help them prepare for caring for a baby with health challenges and, in some cases, can help speed up care following birth.

    “It can be helpful to know about certain conditions, such as heart defects, prior to birth,” Franciskato said. “If we don’t know what’s going on, then we have to run all these tests after birth when we may be on more of a time crunch to treat this baby who’s really sick.”
  • Post-pregnancy. Genetic testing can be performed on baby after birth, too, if health problems or defects are present. This is especially helpful for patients who value that information but don’t feel comfortable undergoing more invasive procedures to obtain that information during pregnancy.

Should you get genetic testing?

A large majority (85%) of pregnant women in the U.S. consider testing and discuss it with their provider. About 40% of women decide to have genetic testing done during pregnancy. The choice is entirely yours. If you’re unsure if it’s is right for you, ask your provider for a referral to a genetic counselor who can help you decide.  

“We’re always available to talk about the chances of having a genetic condition and the benefits and risks of genetic testing,” Franciskato said. “That’s what we’re here for.”

Expert care for you and your baby

Each pregnancy and delivery is unique and yours should be too. Learn more about how Vanderbilt Health’s high-risk obstetrics team, known as maternal-fetal medicine specialists, can provide you and your baby unmatched expert care. With the region’s most advanced care, you and your baby have everything you need, all in one place.

To learn more, call 615-343-5700.

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