There’s a Contraceptive You Can Download

In what is reportedly a global first, a medical auditor recently officially recognized a fertility-tracking app called Natural Cycles as a contraceptive device. This means that British doctors, and possibly also their colleagues in the European Union, can now advise patients on using the app to prevent pregnancy. To many, this designation likely seems odd. But it's almost odder that it took this long for a fertility app to be recognized as a contraceptive tool.

Fertility tracking apps and wearables started popping up here and there about five years ago. By continually logging data tied to ovulation, especially basal body temperature shifts (which indicate the release of an egg), and factoring in the time sperm can survive in a womb, these tools claim to isolate the window of time a woman is most likely to get pregnant with more accuracy than analog monitoring (aka the rhythm method), often thrown off by inconsistent menstrual cycles and pure human error. But there's long been reasonable skepticism within the medical community about the efficacy of these apps—makes sense, given that any and all information it gives about your fertility on a given day would be an estimate (a statistically strong, one but still), and not many people want their likelihood of staying not-pregnant to be reliant on anything so uncertain.

Emerging alongside a spate of press on the downsides of the pill and other birth control methods, this tech has drawn interest from women looking for new contraceptive options. It can't prevent pregnancy during a fertility window or sexually transmitted diseases (ever), but several weeks of glove-less sex with a clean partner with no risk of pregnancy is still attractive to many.

Yet while analog fertility-awareness tracking is a recognized method of birth control (albeit one with an established 25 percent practical use failure rate) and most apps claim to be able to nail fertility windows 89 to 99 percent of the time, few have aggressively marketed themselves as birth control. Hesitant app creators seem to worry they can't offer a sufficiently wide yet solid infertility window, while consumers and experts, as mentioned, worry that the apps' confidence in how protective and accurate they are could be overstated. Natural Cycles was actually ordered to stop calling itself a contraceptive device in 2015 by Swedish medical regulators, and an investigation was launched into its marketing and claims.

"To say this is a method of patient contraception is nothing new at all," says Philadelphia-based OBGYN and fertility expert Nathaniel DeNicola, as it's just a new and potent form of fertility-awareness monitoring. What's novel is the protective power Natural Cycles—along with some similar apps—seem to claim.

Oddly enough, the tech behind Natural Cycles doesn't appear to have changed much since its 2014 launch. It actually seems low-tech compared to other multi-variable wearable detectors and apps on the market. Users just take their under-tongue temperature when they wake up (except on days they feel sick, are hungover, or got less than two hours of sleep) with a two-decimal thermometer and pop the reading into the app. They then wait a couple months for it to calibrate, over which time the fertile window on its calendar narrows. The app sells itself based on the algorithm it uses to read that data, developed based on the statistical modeling founder Elina Berglund Scherwitzl used as a scientist at CERN (working on the team that discovered the Higgs-Boson particle). Her algorithm supposedly takes erratic cycles and other confounding variables into account and grows stronger the more women dump their data into it. However it's not clear whether this proprietary algorithm really gives them a technical boost over competitors.

Raoul Scherwitzl, Berglund's husband and Natural Cycles's co-founder, says one of the reasons they gained regulatory recognition was that they've been able to back up claims that they can offer protection on par with the pill with peer-reviewed data. In 2015 and 2016, researchers at Sweden's Karolinska Institute published two studies showing that, while some women had sex on no-go app calendar days and got pregnant, with proper use women avoided pregnancy on safe-labeled days over 99 percent of the time. The app has a 45 percent dropout rate that may represent people who aren't up to the regular monitoring it requires. But Natural Cycles argues most of their remaining users put in the effort and follow the advice the app provides.

"Regulatory recognition," Scherwitzl told me, "has created greater consumer confidence, which has led to a sharp rise in the number of women using the app." In February it had about 150,000 users now it has "over 200,000 with more [registering] this year than all of last year alone." Ira Hernowitz, CEO of the fertility tracker app Kindara, acknowledges that this recognition has given a limited boost to the industry at large. In the near future, Natural Cycles plans to get Food and Drug Administration recognition as well and expand rapidly into the American market.

However DeNicola and other fertility experts remain skeptical that Natural Cycles could, by an algorithm and digital monitoring alone, close the massive efficacy gap between analog fertility awareness and the pill. DeNicola notes that both of the Karolinska studies were funded by the app, which doesn't negate them but should inspire some suspicion of bias. He also suspects that the app's marketers have massaged their data to make it look optimally appealing.

"To claim if you have a patient who uses [the app] correctly and you are one of the lucky ones who doesn't have a fertile day mislabeled by the app, you have a 0.5 percent chance of pregnancy" is iffy, he says. "Given that this is a significant medical outcome, it's not proper medical advice."

DeNicola actually approves of the app's recognition as a contraceptive and hopes other apps will gain more acceptance and prominence as well. He, like many of his peers, thinks apps can add to popular understandings of fertility and general contraceptive awareness. He just thinks Natural Cycles and other apps shouldn't compare their efficacy to the pill when there's only a limited amount of data to date; doing so may undermine their credibility and their future potential.

Scherwitzl acknowledges that to truly build confidence in the app beyond the new approval, they'll have to hammer out solid guidelines for advising patients on its reasonable use. He also acknowledges that to make big, solid claims about its efficacy as birth control they'll need more clinical data—especially studies they didn't fund themselves. Until then, the contraceptive app space will remain limited, creeping forward amongst women on the hunt for something different, and ideally scaring off those looking for an easy magic bullet.

Update 1/16/18: Natural Cycles has been reported to Swedish authorities after 37 women using it had unintended pregnancies.

Update 8/13/18: The FDA approved Natural Cycles for use in the United States, citing clinical trials with a "typical use" failure rate of 6.5 percent, or 6.5 women out of 100 who use the app for one year getting pregnant because they had sex on a day when the app predicted they wouldn't be fertile or because their contraceptive method failed when they had sex on a fertile day. By comparison, the "typical use" failure rate for the pill is 9 percent and, for the IUD, 1 percent.

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