Natural Cycles is the first app-based method of birth control to earn the government org's stamp of approval.

By Julia Malacoff
August 14, 2018
Photo: Natural Cycles

Going all-natural when it comes to reproductive health is all the rage right now. More women than ever are choosing to skip synthetic hormones in favor of natural methods of birth control because of side effects, certain health conditions, and plain old personal preference. Another natural option? Tracking your fertility via an app. (FYI, here's why everyone is hating on the Pill right now.)

Historically, fertility apps have not exactly been recommended for birth control purposes. Instead, they've been seen by doctors as an option for women who are trying to conceive. Still, many women have been using them as birth control for years, despite warnings that they might not be the best option for effective pregnancy prevention thanks to the probability of user error.

But last week in a plot twist, the FDA released a statement saying they are approving Natural Cycles, a well-known fertility app, to be marketed as a direct-to-consumer form of contraception. That's a pretty big deal, since fertility awareness-the method of birth control the app uses to prevent pregnancy-is somewhat controversial. Here, experts answer all your questions.

What is the fertility awareness method?

Fertility awareness methods use an algorithm in combination with information such as basal body temperature (measured by thermometer first thing in the morning upon waking) to predict days when you're most likely to conceive. On those high-risk-of-conception days, it's recommended that women use extra protection, such as a condom, or abstain from sex. The Natural Cycles app (which comes with an oral basal thermometer and runs $80 per year) marks these days clearly for users so that they can avoid unintended pregnancy. In most cases, it takes three months for the app to establish a baseline and understand your cycle enough to make recommendations, so it's crucial to use back-up birth control, like a condom, during those early months using the app.

Is it the same thing as fertility apps?

So is there a big difference between apps that prevent pregnancy and ones that help women get pregnant? Well, erm, no. The difference is in the marketing, apparently. "These apps identify days in which the user is more likely or less likely to become pregnant," explains Kelly Strutz, Ph.D., an assistant professor in the department of obstetrics, gynecology, and reproductive biology at Michigan State University. That means the same app can be used for both purposes.

"The difference is whether a woman would want to time intercourse for the more likely or less likely days," Strutz says. "And, of course, the consequences of an error are different too. Missing one fertile window when trying to get pregnant is usually no big deal, but unintentionally timing unprotected sex during a fertile window can be life-changing."

How effective is it at preventing pregnancy?

If this app sounds familiar to you, it might be because it was approved for use in the EU as a method of natural birth control in 2017, but at the time, many experts were still wary of using it for this purpose. As Rachel High, D.O., an ob-gyn and fellow at Baylor Scott & White Health told Shape last year, it may be better when used as a transitional method for women coming off hormonal birth control who plan to start a family soon, but *not* for women who wanted to delay pregnancy indefinitely.

That's because lots of things can affect your basal body temperature, she said, (stress, bad sleep, drinking alcohol) and the chances of inaccurate "fertile days" were just too high, in her opinion. This seemed to be the general consensus among doctors in the reproductive health field at the time.

So what's changed? Well, the FDA's announcement points to some interesting stats on the app's effectiveness, especially when compared to more traditional methods of birth control. When used perfectly, the app's fertility awareness method had a failure rate of 1.8 percent. That means that out of every 100 women who used the app (which has been clinically tested on over 15,000 women at this point), only 1.8 got pregnant while using it perfectly. In "typical use," which means perhaps their temperature was not taken at the correct time or they had sex without protection on a day when protection was recommended, the rate rose to 6.5 percent.

For comparison, the Pill has a 1 percent failure rate with perfect use, and a 9 percent failure rate with typical use, according to Planned Parenthood. When you think about it this way, the Natural Cycles app doesn't look too shabby. IUDs, on the other hand, have a less than 1 percent failure rate overall, since there's no room for user error (although they can fail for other reasons, like not being inserted correctly or shifting in position).

So, should you download the app?

The big question: If the fertility awareness method is so amazing, why isn't everyone using it? And why isn't every doctor recommending it? To put it simply, not everyone is a good candidate for it. "Using apps to prevent pregnancy should be recommended only to women with fairly regular cycles, which would exclude women with PCOS and thyroid conditions, among others," Strutz says. (Heads up, knowing these PCOS symptoms could actually save your life.)

It also excludes anyone with an irregular menstrual cycle. "I would recommend Natural Cycles in efforts to avoid pregnancy in normally menstruating women," says Monique Swain, M.D., FACOG, an ob-gyn at Henry Ford Health System. "However, in women with infertility or infertility concerns, I would not recommend using this app as it may not be accurate."

Some doctors have other concerns. "I would not advise patients who wish to avoid pregnancy to count on this app alone," says Tomer Singer, M.D., an ob-gyn with Northwell Health. Mainly, he says, this is because stress, infection, medication, and other external factors can affect ovulation and body temperature, which is the way the app calculates "safe days." In other words, if you really don't want to get pregnant, this is not the safest way to make sure it doesn't happen.

The bottom line? It's crucial to check in with your doctor before relying on an app to prevent pregnancy. And if you do decide to go for it, commit to taking your temperature at the same time every. single. morning.