Prenatal Blood Tests for Baby Are Spotting Cancers in Moms-to-Be

December 5, 2024
Dennis Thompson HealthDay Reporter

Could a prenatal blood test designed to find abnormalities in a fetus also detect hidden cancer in the mom-to-be?

A new study says yes: Scientists report they discovered cancer in nearly half (48%) of expecting mothers with abnormal results on the blood test, known as a prenatal cell-free DNA test.

The cancers included colon, breast, lung, kidney, lymph gland, bile duct and pancreatic cancer, according to research published Dec. 4 in the New England Journal of Medicine.

"They looked like healthy, young women and they reported themselves as being healthy,” said senior researcher Dr. Diana Bianchi, director of the National Institute of Child Health and Human Development, told the Associated Press.

Blood tests are used to check pregnancies for any health problems of either the mom or the fetus.

The prenatal cell-free DNA test analyzes DNA fragments released into the bloodstream by the placenta. It can be used to determine the baby’s sex, or to identify an extra chromosome that will contribute to disorders like Down syndrome.

But this test also can detect DNA fragments leaking from an undetected cancer in mom, researchers noted.

For this study, researchers performed cancer screening on 107 pregnant women using whole-body MRI scans, standard diagnostic testing and cell-free DNA tests.

Of the group, 52 women were diagnosed with cancer. The most common cancers were lymphomas -- 31 of the women had cancer of the lymph glands.

More than half (56%) of the women with cancer had no symptoms of their disease, researchers added.

Another quarter had symptoms that had been ascribed to their pregnancy. For example, stomach pain caused by pancreatic cancer had been diagnosed as acid reflux.

Whole-body MRI scans were most effective at detecting cancers, followed by cell-free DNA tests. Standard diagnostic techniques like taking a medical history and performing a physical exam were least useful.

About 1 in every 10,000 women who get a cell-free DNA test each year will get an abnormal result that’s tough for doctors to interpret, researchers told the AP. These women -- maybe as few as 250 a year in the United States -- could be at risk for cancer.

“They and their care providers need to take the results seriously and have additional testing because in that population there is a 48% risk of cancer,” Bianchi said.

More information

Nemours Children’s Health has more about prenatal tests.

SOURCE: National Institutes of Health, news release, Dec. 4, 2024; Associated Press

Pregnancy Cancer: Misc.