Making Good Choices About Genetic Testing in Pregnancy

6 steps to getting the information you need

Genetic testing has become a routine part of prenatal care. Starting in the first trimester, pregnant women can be screened for multiple conditions that could have a significant impact on a baby. Having more information can be tremendously helpful, but it can also cause additional – and often unnecessary – anxiety. That's why experts want women and couples to understand the tests that are offered, and to know that they have a choice about what tests to have, and whether to have them. 

"Sometimes these tests come across as recommended," says Katie Stoll, director of prenatal genetic services at the Genetic Support Foundation. "But in most cases, prenatal genetic screening should be a choice based on an individual person or couple's needs, values, and beliefs."

But Stoll also points out that our time-crunched healthcare system "is not set up to support thoughtful conversations about why a woman would or would not want to have these tests." And that means it's important for women and their partners to do their own research for the information they need to make good choices. "The first thing that I recommend is for patients is to be self-educated," says Diana Punales-Morejon, PhD, a psychologist and genetic counselor at the City University of New York.

So we went to experts in genetic testing and counseling to create this six-step guide to help you make thoughtful decisions about tests in pregnancy. 

1. Find out your choices.
Ask your doctor or midwife what tests are routinely offered. It's important to know that there are two kinds of tests – screening tests and diagnostic tests. Screening tests cannot tell you whether your baby does or does not have a particular condition. These tests can only determine whether you have anincreased risk of having a baby with a particular condition. On the other hand, diagnostic tests can confirm your baby has a medical condition. Diagnostic tests also carry some risk of miscarriage.

Here are some examples of common screening and diagnostic tests.

Genetic carrier screening: This simple blood test involves an analysis of your (and sometimes your partner's) DNA to determine if you carry a gene for a particular medical condition that you could pass to on to your child. Because these conditions are more common among certain ethnic groups, historically women were only offered carrier screening if their ancestry put them at increased risk. But women are increasingly offered a full panel of testing for more than 100 diseases – often regardless of ethnic background.

Jill Fonda, a senior prenatal genetic counselor at Greater Washington MFM and Genetics in Rockville, Maryland, cautions against automatically choosing the more comprehensive screening. Because both you and your partner have to be carriers in order to pass on a condition to your child, "most people are going to go through that and not both be carriers," explains Fonda. "[This screening] could be anxiety-provoking, so it shouldn't be routine. What should be routine is the right test for the right person." That means having a conversation with your provider about your family and medical history before choosing carrier screening.

First trimester screening: This common screening test is offered to women around 11 or 12 weeks and involves an ultrasound (also called a sonogram) and a blood test. During the ultrasound, a technician examines the amount of fluid in the space at the back of your fetus's neck (nuchal translucency). Having too much fluid there can make that space larger and indicate an increased risk of Down syndrome. Those results are considered with the results of a blood test that measures a pregnancy hormone and protein to come up with a number estimating your risk of giving birth to a child with certain genetic conditions, including Down syndrome.

"The ultrasound that looks for the nuchal translucency is going to identify 70 percent of families with a baby with Down syndrome," says Fonda. Combined with the blood test results, this screening will identify 80 to 90 percent of babies with Down syndrome. 

Cell-free DNA screening: More and more doctors now offer cell-free DNA screening, also known as noninvasive prenatal screening and sold under several brand names including MaterniT21and Harmony. This blood test uses the fetal DNA circulating in the mother's blood to screen for chromosomal abnormalities. It's the most accurate screening test for detecting Down syndrome risk, but it does not screen for all conditions that can be identified using diagnostic tests.

Chorionic villus sampling (CVS) and amniocentesis: These two invasive tests involve inserting a needle into your uterus to collect a sample of complete fetal cells to test for chromosomal abnormalities. These tests can tell you definitively if your baby has a particular condition, but they also have a small risk of miscarriage (about 1 in 500).

2. Learn what information the tests can provide.
"Ask your provider, 'what can I learn from this test, and what could I do with that information?'" recommends Anne Lyerly, MD, associate director of the Center for Bioethics at the University of North Carolina at Chapel Hill. "With screening tests, an abnormal result does not mean you have an abnormal pregnancy, it just means you are a good candidate for further testing." So it's important to ask how you will get the results, what they mean, and what happens if you have an abnormal result.

It's also very important to find out how often the screening test can produce a false positive, meaning the test indicates there is a higher risk of having a child with Down syndrome when your child is chromosomally normal.

Remember that screening tests do not give conclusive answers. "There is not a yes or no answer in a screening test," explains Stoll. "Just a higher or lower chance that your baby has a particular condition." And even an increased chance can still be a very remote one. "But hearing that you are at 'increased risk' can cause a lot of anxiety. For other women, it can be helpful information to help them think through additional tests." 

3. Find out your baseline risk.
"Many women are low risk and will find reassurance by just learning what the probability is to begin with," says Stoll. "Women may perceive they have a high risk, but when they find out the actual statistics they learn it is not as high as they thought."

For instance, your doctor can tell you your risk of having a baby with Down syndrome, based on the age you will be when your baby is due. If your baseline risk feels comfortable to you, you may decide not to screen for the condition.

For other genetic conditions, if you do not have a family history of the condition, your baseline risk is lower (and many of these conditions are extremely rare to begin with), so having additional screening may not seem warranted to you.

4. Ask yourself (and your partner): Why do I want to know?
"A lot of women get screened because they want the results to be normal, and they want to be reassured," says Siobhan Dolan, MD, an ob-gyn geneticist and medical advisor to the March of Dimes. But these tests can have false positives and abnormal results, so it's important to know what steps you would take if you get worrisome or inconclusive information.  

"If amniocentesis is totally off the table for you, then it's worth thinking about whether to have a screening test," suggests Lyerly. For women who do not want to have an amnio, "a screening test that shows increased risk may lead to stress and anxiety for the rest of the pregnancy," says Dolan.

"On the other hand, if it is very important to you to have definitive information about whether your child might have a particular condition, then it makes sense to skip the screening tests (which can unnecessarily raise worry) and go straight to an invasive test such as CVS," says Dolan, "which will give you conclusive information."

5. Talk with a genetic counselor.
Genetic counselors have training in both genetics and counseling and can answer your questions, explain the complicated science behind the tests, and take the time to help you make a good decision. "They have the expertise and time to talk you through choosing these tests and understanding the results," says Dolan.

They can also refer patients to psychologists for further counseling support if needed. "You also have a much better shot of getting a genetic counselor on the phone the next day to talk through any further questions that came up," says Fonda. Most obstetrics practices have a genetic counselor you can consult if you have an abnormal result or are considering an invasive test.

6. Manage the anxiety of making choices and waiting.

Keep things in perspective: "Let's say you're 39, and you're worried about Down syndrome. You know your risk is increased, so find out what your risk is," recommends Fonda. "And if it's 1 percent then flip it: The chance is 99 percent is that your baby doesn't have Down syndrome. So write 99 percent [and hang it] on your refrigerator."

Reach out for support: "A lot of time couples want to keep things private until they get the test results," says Punales-Morejon. But that can make you especially vulnerable because you are experiencing worry without the support of family and friends with whom you normally talk things through. Punales-Morejon says it is worth thinking about sharing your experience with loved ones whom you think will be supportive to help you cope with anxiety.

Know there's no such thing as a perfect decision: When she talks to couples, Fonda tries to help them understand that "there may not be a perfect decision about testing. They have to make the best choice for them. And it may not be analytical. It may be in your gut. You want to be a great mom who makes good decisions but not a perfect mom who makes perfect decisions because they don't exist."