You “like” a video of giggling babies, and your feed is overcome with ads for hand-carved cribs. You re-share a “cute puppies” reel, and adoption centers appear. Social media never hid that it uses user data to sell products. It never says, though, that for women and people who menstruate, that information could be provided by your period tracking app. And in a post-Roe world, that’s the least of our worries.

Period apps use algorithms trained on user data to predict people’s menstrual cycles. They’re promoted as tools of empowerment, helping people make informed bodily choices. As abortion rights fracture across jurisdictions, however, concern grows that deeply intimate data could be weaponized beyond mere profiteering.