On Friday, the first day in a post-Roe America, many women were rushing to delete period tracker apps out of fear the data being used against them in states where abortion is now criminalized. The apps Flo and Clue have 55 million active users combined, NPR reported, raising questions about whether data could be used against them. Clue released a statement saying their app operated under strict European privacy laws, meaning that data is “private and safe.” Flo also launched a feature called “anonymous mode,” and vowed never to sell data. And tech expert Cynthia Conti-Cook told NBC News that prosecutors are far more likely to use evidence like search histories, text messages and emails explicitly showing an intent to end a pregnancy, rather than tracking apps. Many clinics have long used encrypted communication and or paper only, NBC reported. Other experts advised erring on the side of caution. “If I lived in a state where abortion was actively being criminalized, I would not use a period tracker—that’s for sure,” University of Edinburgh researcher Andrea Ford told NPR.