LANSING, Mich. (WLNS) – The FDA has released a new warning about some prenatal screening tests.

The agency warns that pregnant women should consult a genetic counselor beforehand.

“It is a story about the difference between a screening test and a diagnostic test, so what we’re talking about and what the FDA put the alert out about is a noninvasive blood test,” said. Dr. Jennifer Ashton, ABC’s chief medical correspondent.

“It’s pretty standard in prenatal care in this country so over 4 million women get this test around 10 weeks of pregnancy, usually they combine the results with an ultrasound looking at the fetus and what they’re trying to screen for are chromosomal abnormalities like Down syndrome. The issue is that this is a screening test, so it is not 100% accurate and that’s why the FDA is putting out this alert,” said Dr. Ashton.

According to Dr. Ashton, the test is about 97% to 99% accurate, but then if it flags an increased risk for a potential problem, the standard of care is an amniocentesis or CVS, which is a diagnostic test.

“That looks at the DNA and what the FDA is worried about is that women may make incorrect decisions about continuing their pregnancy based on this result.”