When Screening for Genetic Abnormalities, Noninvasive Prenatal Tests Often Result in False Positives—Here's What That Means

An investigation by The New York Times found that 85 percent of NIPTs result in false positives.

An image of a pregnant woman sitting on a bed at home.
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Earlier this week, The New York Times published a groundbreaking analysis of noninvasive prenatal tests (NIPTs), finding that they produce inaccurate results up to 85 percent of the time. If you are a pregnant person, or someone who hopes to become pregnant in the future, this news may have caught you off guard and made you feel concerned.

That's totally understandable—these are worrisome stats and you may be unsure about what this all means for you. You may be wondering if you should get any NIPT screenings at all. If you've received concerning results from one of these tests, you may feel unsure of what the results mean and what additional steps you should take.

The topic of NIPTs can be a confusing one, and the information can feel very technical and difficult to understand. Let's break it all down and look at what NIPTs actually are, what they're used for, and how this new data from The Times fits into it all.

What Are NIPT Tests?

NIPT tests are screening tests used to find out if your baby might be born with a genetic abnormality. These tests are noninvasive and analyze a sample of your blood for DNA from your fetus. During pregnancy, small fragments of your baby's placenta DNA end up in your bloodstream and can be detected and analyzed. These free-floating DNA fragments are called cfDNA and may contain information about your baby's genetic makeup.

Some folks use NIPT tests to try to find out their baby's sex under the assumption they are learning their baby's gender. Unfortunately, these tests don't accurately determine one's gender identity and they can also result in unnecessary worries.

It's important to understand that NIPT tests are screening tests. In other words, they are not definitive results about what genetic abnormalities your baby might have. They can tell you whether your baby has an increased or decreased risk of having a genetic abnormality, not whether they actually do.

You will need a diagnostic test, such as amniocentesis and chorionic villus sampling to confirm or deny the results from a NIPT test. These diagnostic tests can be informative, but they slightly increase your risk of miscarriage.

How Common Are False Positives?

NIPT tests can screen you for many different genetic abnormalities. According to The New York Times, they are thought to be highly accurate in terms of accessing your baby's risk for Down syndrome, which was one of the first uses of these tests. However, when it comes to more rare genetic abnormalities, there are more possibilities for false positives.

In their independent investigation, The New York Times looked at studies and interviewed researchers about five different prenatal tests that screened for rare genetic conditions. The screenings they analyzed included tests that looked for DiGeorge syndrome, 1p36 deletion, Cri-du-chat syndrome, Wolf-Hirschhorn syndrome, and Prader-Willi and Angelman syndromes.

These are extremely rare conditions—for example, Wolf-Hirschhorn syndrome affects 1 in 20,000 births—but can cause lifelong physical and intellectual disabilities. Results varied from one test to another, but The Times found that these tests consistently gave inaccurate results on average 85 percent of the time.

What Does This Mean For You?

Hearing that your baby might have a genetic condition that could result in disability (and in some cases death) can be difficult information to absorb. Learning that these tests can be highly inaccurate a lot of time may make you question whether they are even worth pursuing.

These are valid concerns, and it's part of why The Times made this information public for parents. The truth is, though, the decision to get one of these tests is an individual choice, one you should make after a conversation with your medical team, rather than based on a knee-jerk reaction to some unsettling statistics.

Should You Get A NIPT Test?

For many expectant parents, getting screened for a rare genetic condition that comes with a high probability of inaccurate results, is simply not worth the stress. Blood tests for genetic abnormalities are usually conducted in the first 10-14 weeks of pregnancy, and follow-up diagnostic tests are usually done between the 15th and 20th week of pregnancy.

So, if your NIPT test tells you that your baby might have one of these conditions, there will be a waiting period until you are able to get a diagnostic test to tell you whether your baby does, in fact, have one of these conditions. Then you have to wait for results for the diagnostic tests.

All of the waiting and the anxiety that comes with testing may not be worth it for you, especially when considering a screening test with a high rate of false positives. However, people who have known risk factors, such as genetic conditions that run in their family may decide that these tests are vital.

The American College of Obstetricians and Gynecologists (ACOG) recommends that all pregnant individuals be offered NIPT screenings whether or not they have a known risk factor, including advanced age. This doesn't mean that your doctor will recommend that you get screened for every genetic condition, though.

For example, almost all health care providers recommend that parents over the age of 35 be screened for Down syndrome but may not recommend one of the more rare genetic screenings that The Times investigated. The decision about which genetic conditions to screen for should be done in collaboration with your health care provider.

Where To Go From Here

Seeing a scary headline about genetic tests and high false positives can be enough to increase your blood pressure; but knowledge is power.

Even though you may feel overwhelmed as you absorb this information, keep in mind that you have choices when it comes to your prenatal care. Learning that screenings tests like NIPTs sometimes can be inaccurate is a great opportunity for you to have an open discussion with your health care provider about what your options are and which screening tests make sense for you and your pregnancy.

If you are personally dealing with some upsetting results from a NIPT screening and waiting for further confirmation, know that you aren't alone: Many parents have navigated these extremely stressful situations.

Again, speaking to your health care provider about what this means, how accurate these results are, and what your next steps should be, is important. If you feel that your provider isn't listening to you, or isn't communicating in a clear way, you might consider switching providers or getting a second opinion.

Importantly, the mental health impact of dealing with screening, testing, and upsetting results should not be underestimated. If you are experiencing heightened stress or anxiety, please reach out to your health care provider or a mental health professional. You deserve to feel balanced and well.

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