A new kind of blood test can screen for many cancers — as some pregnant people learn

When women get a blood test during pregnancy that looks at free-floating DNA, they expect it to tell about the health of the fetus. But the test sometimes finds signs of cancer in the mother. (Isabel Seliger for NPR)

When Kathleen Aukstikalnis was expecting her first baby, she turned to a common prenatal test that a lot of her friends had gotten done during their pregnancies.

The simple blood test looks at DNA that's floating freely in a pregnant person's bloodstream. It searches for bits released by cells in the placenta, which should have the same genetic make-up as the fetus.