An anonymous reader shares a report: A contraceptive mobile phone app used by tens of thousands of British women has come under fire after reportedly sparking a string of unwanted pregnancies. Swedish birth control app Natural Cycles, which costs $55, tracks body temperature to accurately predict when in the month a woman is more likely to fall pregnant. The period monitor was hailed as a non-mood altering alternative to the pill and, if used perfectly, was found to be 99 per cent effective by researchers. But the app has come under fire after the Sodersjukhuset hospital in Stockholm lodged a complaint with the Swedish Medical Products Agency, the country's government body responsible for regulation of medical devices. It claimed staff at the hospital had recorded 37 women who had fallen pregnant in the last quarter of 2017 after using the app. One midwife said the hospital had a duty to report all side effects.