A contraceptive app has been reported to a medical regulator in Sweden after being blamed for 37 unwanted pregnancies. 

The Natural Cycles app, which has nearly 700,000 users worldwide, is designed to work by scanning women’s body temperature during their menstrual cycle to inform them when they can have unprotected sex. Those days show up in green on a calendar. On the days marked in red, couples are advised to use other contraceptive methods such as condoms. Last year, Natural Cycles released a study it funded stating that the app was more effective than the contraceptive pill. 

Södersjukhuset hospital in Stockholm reported Natural Cycles to the Swedish Medical Products Agency — a government body that regulates medical devices — after 37 women who used the app sought abortions at the hospital from September 2017 to the end of the year, according to Swedish outlet SVT.

“No contraception is 100 percent effective, and unwanted pregnancies is an unfortunate risk with any contraception,” Natural Cycles said in a statement. “Natural Cycles has a Pearl Index of 7, which means it is 93 percent effective at typical use, which we also communicate. Our studies have repeatedly shown that our app provides a high level of effectiveness similar to other methods.”

Natural Cycles said it hasn’t received any information from Södersjukhuset hospital, but it’s in touch with the Medical Products Agency and is responding to each individual reported case.

“At first sight, the numbers mentioned in the media are not surprising given the popularity of the app and in line with our efficacy rates,” the statement continues. “We have initiated an internal investigation with our clinical department in order to confirm this.”

Natural Cycles became the first app officially certified for contraception use in February after being approved by Germany’s Department of Health. This latest finding could jeopardize the app’s chances at getting approval from the US Food and Drug Administration.

More women are turning to apps to help with birth control. An app like Natural Cycles may seem like an ideal solution, but this latest incident is a cautionary tale to not become too reliant on a digital platform until there’s enough data to back its efficacy.  

For its part, Natural Cycles said incidents like these are just a natural part of the process.

“As our user base increases, so will the amount of unintended pregnancies coming from Natural Cycles app users, which is an inevitable reality.”

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