The app has been certified as a method of birth control in the European Union, NPR reported.
The app’s creator, Elina Berglund, is a particle physicist. For 10 years she relied on a hormonal birth control implant, but she wanted to start a family yet still wanted a natural way to avoid pregnancy. None of the existing apps worked for her, so she and her husband used math to create one.
“You were looking at women’s temperatures and data, which was a lot of fun,” Berglund told NPR.
Berglund and her husband launched the app, Natural Cycles, in Sweden in 2014. It relies on a woman’s daily temperature to determine fertility. When the risk of pregnancy is high, a red light flashes. A green light means the chances of getting pregnant are low.
In a clinical study of 4,000 women who used the app, the results were better than traditional fertility awareness methods, NPR reported.
Just seven out of 100 women got pregnant. compared to about 24 out of 100 using the rhythm or calendar method.