Algorithm method: birth control app is reported to Swedish officials after 37 unwanted pregnancies

A much-hyped birth control app has been reported to Swedish authorities after a hospital found 37 cases of unwanted pregnancies among women relying on the app for contraception.

Natural Cycles, a smartphone application that marries hi-tech with the old-fashioned rhythm method, last year became the first app to be certified as a contraceptive method in Europe. The app requires women to input their temperature every morning, then calculates the users’ menstrual cycle and informs them when they can have sex without protection.

The Stockholm-based company, founded by Cern physicist Elina Berglund and her husband, Raoul Scherwitzl, claims to be 93 per cent effective with typical use – and without the side effects that many women experience from hormonal birth control.

But the start-up is now on the defensive after the Swedish public broadcaster SVT reported that 37 of the 668 women who sought an abortion at one of Stockholm’s largest hospitals from September to December 2017 were relying on Natural Cycles for birth control.

The hospital reported the app to Sweden’s Medical Products Agency, and Natural Cycles said in a statement that it was “responding to each reported case”.

“An unwanted pregnancy is, of course, very unfortunate and we deeply care every time one of our users becomes pregnant unplanned,” the company said. “As our user base increases, so will the number of unplanned pregnancies coming from Natural Cycles users. This is an arithmetic truth applicable to all contraceptive methods.”

A 93 per cent effectiveness rate means that out of every 100 women using the app, seven will experience an unwanted pregnancy. Those figures are about comparable with typical use of oral contraceptives, and better than condoms or other barrier methods, according to the Centre for Disease Control.

The traditional rhythm method, which involves tracking one’s cycle without the assistance of a nuclear physicist’s algorithm, has a typical use failure rate of 24 per cent.