For pregnant women, abnormal results from certain prenatal tests may signal something is wrong with the moms-to-be, not the fetus.
That's according to a preliminary study that says very rarely, these results may indicate cancer when follow-up testing indicates a healthy fetus.
Prenatal blood tests are increasingly being used to detect fetal chromosome abnormalities, including Down syndrome. They test pregnant women's blood, which contain small amounts of fetal DNA. But cancer is among conditions that can cause results that mistakenly indicate an abnormality in the fetus.  The results echo smaller studies but they're not definitive.
The researchers say more studies are needed to help doctors decide how to advise women about these tests.
The study was published online Monday in the Journal of the American Medical Association.

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