Prenatal testing: Is it right for me?

September, 25th, 2024

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Pregnancy can be a time of high hopes — and sometimes, worries. You might wonder if your baby is at risk of being born with a physical health condition called a birth defect. You can choose to get tests that check for things that may raise the risk of birth defects, such as genetic conditions. Depending on the results of those tests, you also may want to get tests that find out whether your baby might have a health condition at birth. Here’s what you need to know about your options.

Prenatal testing for genetic conditions

Many health concerns present at birth are due to genetic conditions. Genetic conditions are caused by changes in genes or threadlike pieces of DNA called chromosomes. The two main types of testing for genetic conditions during pregnancy are:

• Screening tests. Prenatal screening tests can find out whether your baby is more or less likely to have certain genetic conditions. Most often, these screening tests are offered during the first or second trimester of pregnancy. They include blood tests and ultrasound. Irregular results on a screening test don’t mean that your baby has a genetic condition. Your healthcare professional can help you decide whether you should get diagnostic tests to find out for sure.
• Diagnostic tests. These tests are the only way to know whether your baby has a genetic condition. You can get a diagnostic test if a screening test finds that your baby has a higher risk of a genetic condition. Or you could think about getting a diagnostic test if your age, family history or health history raises your baby’s risk of a genetic condition. Some diagnostic tests carry a slight risk of miscarriage. These tests include chorionic villus sampling and amniocentesis.

Types of screening tests

Prenatal screening tests for genetic conditions include:

• First trimester screening tests. During your first trimester, your healthcare professional can offer a blood test and an ultrasound. The blood test measures certain substances in your blood. The ultrasound measures the size of the clear space in the tissue at the back of your baby’s neck. This type of ultrasound is called a nuchal translucency test. In Down syndrome and some other genetic conditions, the nuchal translucency measurement is larger than usual.
• Second trimester screening tests. During your second trimester, your healthcare professional may offer another blood test called the quad screen. This test measures the levels of four substances in the blood. Results show your risk of carrying a baby who has certain genetic conditions caused by chromosome changes. These conditions include Down syndrome and trisomy 18. The test also can check for a higher risk of conditions that involve the brain or spinal cord. These are called neural tube defects. Another second trimester screening test is a routine ultrasound of your baby’s anatomy. This ultrasound is recommended for every pregnancy.
• Prenatal cell-free DNA screening. This blood test can be done in any trimester. It checks the baby’s DNA in the pregnant person’s bloodstream. It looks for a higher risk of specific genetic conditions such as Down syndrome and trisomy 18. This screening test also can provide information about a baby’s sex.

Questions to ask yourself

Prenatal tests for genetic conditions are optional. It’s important to make an informed decision about testing. That’s especially important if you get tested for rare conditions that don’t yet have treatments.

Before you go forward with testing, ask yourself these questions:

• What will you do with the test results? Test results within the standard range may ease your worry. But if prenatal testing suggests that your baby might have a genetic condition, you could be faced with certain decisions. For example, you might have to think about whether to continue the pregnancy. Or you might welcome the chance to plan for your baby’s care in advance.
• Will the information shape your prenatal care? Some prenatal tests find health conditions that can be treated during pregnancy. Other times, prenatal testing alerts your healthcare professional to a condition that needs treatment right after birth.
• How accurate are the results? Prenatal screening tests aren’t perfect. The rate of wrong results varies from test to test. You can ask your healthcare professional for information about these rates. There are different kinds of wrong results. A test result called a false-positive shows a health risk when there really isn’t one. A result called a false-negative shows no health risk when there really is one.
• What are the risks? Weigh the pros and cons of each test with your healthcare professional. For example, some tests may raise the risk of anxiety, pain or a miscarriage. Think about whether those risks are worth the value of getting answers from the tests.

The choice of whether to get prenatal testing for genetic conditions is up to you. If you’re concerned about testing, talk with your healthcare professional about the risks and benefits. You also may meet with a genetic counselor. This healthcare professional can help you choose a test and understand the results.

Taking the time to think about your options can help you make the best decision for you and your baby.