FDA Report Warns Against False Positives in Some Prenatal Genetic Tests

Here’s what to know.
save article
profile picture of Nehal Aggarwal
By Nehal Aggarwal, Editor
Updated April 21, 2022
lab technician holding vial of blood for blood testing
Image: Juliya Shangarey/Shutterstock

A new report from the Food and Drug Administration is warning parents-to-be about the potential risks of false positive results with noninvasive prenatal tests (NIPTs). This type of prenatal genetic testing is a helpful screening tool that’s widely used during pregnancy, but the FDA stresses that it’s not a diagnostic test, and results and next steps should always be discussed with your healthcare provider.

NIPTs are blood tests designed to look for genetic (chromosal) abnormalities and disorders in baby. The tests are used by almost a third of American pregnant women, and while the results aren’t a confirmed diagnosis, they do tend to have a good accuracy rate for certain genetic disorders, like Down Syndrome. A negative result is generally greater than 99.9 percent, according to the FDA, while a positive result for Down syndrome is about 90 percent accurate.

However, the American College of Obstetricians and Gynecologists (ACOG) doesn’t recommend using NIPT to detect microdeletions, which occur when a very small part of a chromosome is missing, and the consequential disorders are often rare. A New York Times investigation published in January 2022 looked into high false positive rates for NIPTs that tested for microdeletions and rare conditions. It found that some of the tests were marketed in a misleading way and reported that some women had terminated their pregnancies as a result.

According to the FDA, how accurately a NIPT test can predict baby’s risk for a genetic abnormality is dependent on how common that abnormality is. Due to this, when testing for microdeletions and rare conditions, the likelihood of false positive results is high—according to the FDA, the positive predictive value can range from 2 to 30 percent, depending on the condition.

While widely used by healthcare providers, NIPTs are not regulated by the FDA. This is because they’re considered lab-developed tests rather than diagnostic tests. As screening tools, these tests can indicate the level of risk for a genetic abnormality, but they can’t definitely confirm or rule out such abnormalities.

In its report, the FDA urges patients and healthcare providers to weigh the risks and benefits of NIPTs. If the patient does opt for them, the agency says the patient, provider and genetic counselors should review NIPT results together and determine next steps. They also advise performing additional diagnostic testing where needed, rather than acting on NIPT results alone, as these tests have limitations. NIPT results can be influenced by technical issues, as well as biological factors. For example, a positive result may be accurately detecting a chromosomal abnormality in the placenta, rather than baby, who might be completely healthy.

The American College of Obstetricians and Gynecologists (ACOG), the Society for Maternal-Fetal Medicine (SMFM) and the American College of Medical Genetics and Genomics (ACMG) all maintain the following recommendations:

ACOG does not recommend using NIPTs to test for microdeletions. The ACMG recommends against testing for missing or extra chromosomes other than those relating to Down syndrome, Edwards syndrome and Patau syndrome. Prenatal genetic screening should be discussed with and offered to all pregnant people regardless of their age or risk for a chromosomal abnormality. Healthcare providers should educate patients on the positive predictive value of NIPT to support an informed decision on whether or not to undergo testing; they should also emphasize that these tests are meant as screening rather than diagnostic tools.

Looking ahead, the agency is working to closely monitor safety issues around the use of NIPTs. Congress is also considering passing the VALID Act, which would allow the FDA to regulate lab-developed tests.

To learn more about the FDA’s report, visit FDA.Gov.

Please note: The Bump and the materials and information it contains are not intended to, and do not constitute, medical or other health advice or diagnosis and should not be used as such. You should always consult with a qualified physician or health professional about your specific circumstances.

save article
Article removed.
Name added. View Your List

Next on Your Reading List

pregnant woman undergoing nonstress test
Why Your Doctor Might Recommend a Nonstress Test Later in Pregnancy
Medically Reviewed by Kendra Segura, MD
doctor measuring pregnant woman's fundal height
Fundal Height: Why Is My Doctor Measuring My Belly?
Medically Reviewed by Kendra Segura, MD
doctor speaking with female patient medical office
Your Comprehensive Guide to Non-Invasive Prenatal Testing
Medically Reviewed by Kendra Segura, MD
pregnant woman lying on exam table getting an ultrasound
Your Complete Guide to Pregnancy Ultrasounds
Medically Reviewed by Kendra Segura, MD
pregnant woman holding photo of ultrasound
What Is the Nuchal Translucency Ultrasound?
Medically Reviewed by Kendra Segura, MD
pregnant woman getting an ultrasound
Why You Might Need a Biophysical Profile in Pregnancy
Medically Reviewed by Kendra Segura, MD
gynecologist checking pregnant woman's cervix in exam room
Is a Cervix Check Always Necessary in Late Pregnancy?
Medically Reviewed by Kendra Segura, MD
pregnant woman at prenatal doctor appointment
Your Complete Guide to Prenatal Testing
Medically Reviewed by Kendra Segura, MD
overhead view of woman getting first trimester ultrasound
Everything You Need to Know About the First Trimester Screening
By Dani Wolfe
Understanding the Glucose Screening and Glucose Tolerance Test
Understanding the Glucose Screening and Glucose Tolerance Test
Medically Reviewed by Kendra Segura, MD
fetal doppler heart rate of in utero baby
Are At-Home Fetal Dopplers Safe?
Medically Reviewed by Kendra Segura, MD
black and white image of a family ancestry tree
Your Guide to Genetic Testing During Pregnancy
By Ashley Zielger
Same sex pregnant couple at home with their daughter on the couch.
What Is Amniocentesis?
By Rachel Morris
Pregnant woman and her partner happily looking at their sonogram.
Sonogram vs. Ultrasound: What’s the Difference?
By Christin Perry
medical doctor speaking with patient
3D Ultrasound: Why It’s Used and What You Can Expect to See
By Korin Miller
Q&A: Why CVS/amnio?
Q&A: Why CVS/amnio?
By Paula Kashtan
pregnant woman in kitchen by window looking at her phone
Rh Incompatibility: What to Know if You’re Rh Negative and Pregnant
By Lexi Dwyer
happy couple looking at positive pregnancy test
11 Moms-to-Be Share What They Did With Their Positive Pregnancy Tests
By Ashlee Neuman
pregnant woman looking at sonogram
There May Be a New Noninvasive Way to Diagnose Fetal Genetic Disorders
By Ashley Edwards Walker
crate full of fresh veggies and fruits
Here’s How to Tell if Baby Is at Risk for Childhood Obesity During Pregnancy, Study Says
By Stephanie Grassullo
Article removed.