Being unmarried is a cause for stillbirth?!

Brittany • 10.21.17👨‍👩‍👧 | TTC Baby #2!
Hi ladies, I was just reading some stuff about stillbirth on the CDC website for shits and giggles just learning about all sorts of things and taking in information. I don't know if they're biased about having a baby out of wedlock and if they're even allowed to be biased but it said that a woman's possibility of having a sillbirth is increased if they're unmarried... and even can cause preterm labor! Am I just misunderstanding something here? I have pregnancy brain so maybe I'm just misinterpreting their reason for putting that there.