Carrie Breton

Fundamentally, their job is to protect the cell.

One way bodies deal with heat stress is to ramp up the production of molecules called heat shock proteins.

That's Carrie Breton.

She's an environmental epidemiologist at Washington University in St.

Louis.

She says that's extra important during pregnancy, when feeling too much heat can affect both mother and fetus.

The new study in Environmental Science and Technology shows that heat exposure ramped up the amount of protective heat shock proteins in most pregnant women's blood.

But some women who developed lots of the proteins ended up having their babies early.

It's a hint about why some pregnant people might be more sensitive to heat than others.

Alejandra Burunda, NPR News.