Chronic stress and preterm birth linked in surprising way

This is certainly surprising - the experiences need not have occurred anywhere near the time of conception. I'm not sure what "adverse childhood experiences" are however. This is interesting though - I'd like to see what follow-up studies have to say and whether the findings hold up.

“Chronic stress is one of the better predictors of preterm birth,” says Olson, a professor of obstetrics and gynecology in the University of Alberta’s Faculty of Medicine & Dentistry. “In fact, if women are exposed to two or more adverse childhood experiences while growing up, their risk of preterm birth doubles.”