A mobile app that bills itself as “digital birth control” has received marketing approval from the U.S. Food and Drug Administration, but it’s still under investigation in Sweden and the United Kingdom for resulting in dozens of unwanted pregnancies.

The app, Natural Cycles, costs about $80 per year and comes with an oral basal thermometer. The Stockholm-based company claims the app is 93 percent effective under typical use, and 99 percent effective if users follow directions perfectly. Essentially, Natural Cycles uses an algorithm that predicts when a woman is most likely to be fertile based on daily body-temperature readings and menstrual cycle information.

This is the first time the FDA has allowed a birth control app to market itself as a contraceptive.

"Consumers are increasingly using digital health technologies to inform their everyday health decisions, and this new app can provide an effective method of contraception if it’s used carefully and correctly," Terri Cornelison, assistant director for the health of women in the FDA’s Center for Devices and Radiological Health, said in a statement on Friday. "But women should know that no form of contraception works perfectly, so an unplanned pregnancy could still result from correct usage of this device."

In the U.K., the Advertising Standards Authority launched an investigation into the company’s marketing in July after receiving three complaints regarding Natural Cycles’ paid advertising on Facebook, which described the app as highly accurate, according to the Guardian. The Family Planning Association, a U.K.-based charity, told the Guardian it was concerned about Natural Cycles billing itself as a contraceptive.

And in Sweden, a hospital reported 37 cases of unwanted pregnancies among women using the app, according to a January report from the Verge. The Swedish Medical Product Agency confirmed in an email to VICE News that its inquiry into the Natural Cycles app is still ongoing, and that the agency expects to finalize the investigation by September.

Deborah Kotz, a spokeswoman with the FDA, said the agency wouldn’t comment on the U.K. investigation as the U.S. has its own marketing regulations it’ll expect Natural Cycles to follow. However, she said the FDA has reached out to Swedish authorities and is aware of their investigation.

“An increase in the absolute numbers of unintended pregnancies is expected with a growing number of users,” Kotz told VICE News. “We reached out to the Swedish authorities and feel that the information regarding the pregnancies in Sweden is consistent with our knowledge concerning the pregnancy risks associated with use of this device.”