No—temperature-supported period apps labeled fertile days as safe in 41% of cycles studied. The study examined 543,167 cycles from people using a fertility app. It compared calendar-based tracking, tracking supported by Basal Body Temperature (BBT), and a regulated digital birth control tool. That last tool had U.S. clearance and European certification for contraception. Researchers used urine tests for LH (Luteinizing Hormone), a hormone that helps signal egg release. These tests identified days when pregnancy was possible. Calendar-based tracking labeled at least one fertile day as safe in 67% of cycles. Its average predicted pregnancy risk was 22% per cycle. Adding temperature readings reduced those errors, but did not remove them. For temperature-supported tracking, predicted pregnancy risk was 9% per cycle. The regulated tool had at least one wrongly labeled day in 3% of cycles. Its predicted pregnancy risk was 0.5% per cycle. These results apply to the tool studied, not every digital birth control product. These were predicted risks, not counts of actual pregnancies. The study examined existing records rather than assigning people different tracking methods. Still, its main message was clear: ordinary period trackers often missed days when pregnancy was possible. For BioSocial members, this separates recording a useful measurement from trusting an app’s label. A detailed chart does not make a “safe” label reliable. Comparing your own readings and app labels with community peers can help frame discussions. Notes about the app used also matter when comparing experiences. What differences have you noticed between your own tracking records and your app’s predictions?