The FDA says the Natural Cycles app can be marketed as a way to prevent pregnancies, but experts warn that there's no guarantee. 

By Amanda MacMillan
August 14, 2018

Tracking your cycle in hopes of getting—or not getting—pregnant? You probably know by now that there’s an app for that; many, in fact. But for the first time, the U.S. Food and Drug Administration (FDA) has given permission for one of those apps, Natural Cycles, to officially be marketed as a method of contraception. Yup, that’s right: The rhythm method has gone high-tech, and it’s got the government’s seal of approval.

What Friday’s announcement means, exactly, is that the Natural Cycles mobile app can be advertised as a way to prevent pregnancy and an alternative to traditional birth control methods like the pill or IUD. The app, which is intended for pre-menopausal women 18 and older, displays the message “Use Protection” on days when women may be ovulating. It uses data from users’ past menstrual cycles, along with their daily temperature readings, to determine when women are likely to be most fertile. On those days, women should either use a condom or another barrier method, or abstain from vaginal intercourse, if they're using the app as birth control. 

That may sound great for women looking for a drug-free, all-natural way to keep control over their bodies and their reproductive cycles. But the new app is not without controversy. For starters, using the app isn’t as simple as some women might think: It requires users to take their temperature at least five days a week, first thing in the morning, as close to the same time every day as possible.

“If you’re not able to remember to take a pill every day, the app is a little nicer because it will remind you,” says Rebecca Simmons, PhD, an assistant professor in the division of family planning at the University of Utah. “But there’s still something you need to be doing every single day, and that’s definitely something women need to consider.” Temperature can also be affected by things like travel, sleep loss, and irregular schedules, she adds. 

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Natural Cycles also isn’t one of those dime-a-dozen period-tracker apps; a subscription to the service costs $79.99 a year. The FDA’s new designation may open the door for health insurance companies to cover the subscription cost as a form of contraception, says Simmons, but it’s still unclear if or when that might happen.

In the FDA’s press announcement, Terri Cornelison, MD, PhD, assistant director for the health of women in the agency’s Center for Devices and Radiological Health, said that Natural Cycles “can provide an effective method of contraception if it’s used carefully and correctly.” She also added, however, that “women should know that no form of contraception works perfectly, so an unplanned pregnancy could still result from correct usage of this device.”

Speaking of careful and correct use, the app had a “perfect use” failure rate of 1.8% in clinical trials involving more than 15,000 women. That means that only 1.8 out of every 100 women who used the app for an average of eight months became pregnant when they weren’t trying—either because they were fertile when the app said they weren’t, or because their method of contraception failed on a fertile day.

But when researchers looked at “typical use” of the app—which accounted for women sometimes not using the app correctly or having unprotected sex on fertile days—the failure rate increased to 6.5%. By comparison, the “typical use” failure rate of the pill, patch, or ring is 9%. Both of those rates fall somewhere in between the less-than-1% failure rate for IUDs and implants and the 24% failure rate for “fertility-awareness based methods,” i.e. natural family planning.

Those numbers suggest that Natural Cycles works at least as well as some popular birth control methods, and certainly better than tracking your cycle without an app. Simmons agrees: “There’s really only a pretty limited window each menstrual cycle you can actually become pregnant,” she explains. “If you understand that window and you behave appropriately, you can avoid pregnancy pretty accurately.”

But some experts are still concerned. As Vice reported yesterday, the app was recently blamed for dozens of unwanted pregnancies in Sweden and the United Kingdom. When asked about these reports, a spokesperson for the FDA told Vice that the agency had considered them, and that “an increase in the absolute number of unintended pregnancies is expected with a growing number of users.”

There are other things for women to think about if they’re considering trying this app, as well: Like all non­-barrier forms of birth control, Natural Cycles does not protect against sexually transmitted infections. It also shouldn’t be used by women for whom pregnancy could be harmful to themselves or to a developing fetus, says the FDA.

“You may also need to navigate which days you can have sex with your partner, or you may need to navigate condom use,” Simmons points out. (With hormonal birth control, on the other hand, ovulation is prevented—so you’re good-to-go for sex any time of the month.) “If you have a partner who’s not supportive of that, that might be a problem.”

According to Natural Cycle’s website, the app works effectively from the beginning but takes one to three cycles to “get to know you,” which is why women may be told to use protection more often when they first start using the app. (On average, users get about 10 of these “red days” per cycle.) Women switching from the pill or another hormonal contraceptive method should wait about a week before starting the app, the company says.

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The bottom line, says Simmons, is that women have many options when considering birth control methods. In fact, at the same time the FDA approved the marketing of this app, it also approved a new vaginal ring that can be used for an entire year.

“We know that women are more likely to use contraceptive methods when they have a variety of methods available to them, and the reality is that not every method is going to work for every women,” she says. “This is really exciting, in the sense that the more methods we have, the more likely it is that people can find something that works for them—and then can avoid unwanted pregnancy.”