A women’s fertility app that innocuously claims to help women gain a better understanding of their menstrual cycles is secretly funded by anti-abortion, anti-gay, pro-Catholic campaigners, The Guardian reports. The FEMM app is hugely popular—it’s been downloaded more than 400,000 times since 2015 by users from all over the world. A lot of its money reportedly comes from private donors, including the Chiaroscuro Foundation—a charity backed by Catholic hedge-funder and anti-abortion activist Sean Fieler. The foundation handed $1.79m to FEMM developers over the last three years. The app collects personal information about sex and menstruation from users, and doesn’t make the beliefs of its funders clear to users. It markets itself as a way to “avoid or achieve pregnancy.” Anna Halpine, CEO of the FEMM Foundation, said the beliefs of the group and its funders are irrelevant because the app is “not dealing with the question of abortion.”