Your Fertility App Probably Doesn’t Work, New Study Says

Although many women turn to apps like Glow to avoid the side effects of hormonal birth control, researchers say that only a few can really help you avoid pregnancy.

by Candace Bryan
Jul 18 2016, 6:51pm

Photo by Jovo Jovanovic via Stocksy

This week in things you suspected all along: A new study says it may be unwise to trust a fertility app to help you avoid pregnancy. Researchers analyzing 40 fertility and period-tracking apps found that only a select few can be trusted to accurately predict fertility.

Fertility awareness methods (FAMs) are a family of non-hormonal birth control techniques that involve using body signals, such as menstruation and hormones in urine, to predict times of the month that a woman will be fertile. As a birth control method, using FAMs means abstaining from vaginal intercourse (or using alternate birth control) during this predicted fertility window. Evidence has shown that, though 25 percent of couples who use this method experience an unplanned pregnancy, only one in nine women who use them will become pregnant if they use them correctly and consistently.

Read more: What Happens When You Swap Birth Control Pills for an App

While fertility monitoring is commonly used to predict fertility for women who do want to become pregnant, many women turn to the methods as an alternative to hormonal birth control options because FAMs have no medical side effects. However, the new study, published in the Journal of the American Board of Family Medicine, shows that most of the apps aimed at helping women estimate their fertility window often make inaccurate predictions.

To identify which apps to study, researchers initially targeted 95 programs using iTunes, Google, and Google Play searches, some of which have been downloaded over one million times. After eliminating the 55 apps that specifically came with a disclaimer saying they couldn't prevent pregnancy or did not claim to have been developed on evidence, researchers evaluated the apps based on several criteria, including authority, accuracy, user support, and ease of use. Only six—Ovulation Mentor,, iCycleBeads, LilyPro, Lady Cycle, and—predicted fertility days based on data entered by app users perfectly accurately or didn't show any false negatives. The popular app Glow performed the worst of the 30 apps that predicted users' fertile days.

According to the study, this is because many apps are not using "evidence-based fertility awareness-based methods," instead relying on algorithms that have not been peer-reviewed, and are therefore not scientifically sound. The result is that most apps often incorrectly predict a woman's fertility window—including false negatives, where fertile days are marked as non-fertile by the app.

Women are smart—they are smarter than smartphones.

Dr. Marguerite Duane, the study's lead author, tells Broadly that many of these apps rely simply on calendar methods, which can be misleading. "Some apps request information, such as temperature or cervical fluid, but in the end those apps still predict fertility windows solely based on calendar days." That's why Duane says women shouldn't rely solely on these apps to inform them about fertility windows.

"If a woman learns how to use fertility awareness–based methods, she can predict her own fertility window—she doesn't need an app to predict it for her," she says. According to Duane, research has proven fertility awareness to be an effective birth control method, but only when users have been trained by a certified instructor. Even then, studies show that "women take a couple of months to feel confident using the method," according to Duane.

Duane says that an instructor offers benefits no app can provide, such as help recognizing biomarkers and deciphering fertility signs, such as discharge consistency, which can differ from woman to woman. Alongside this kind of personalized training, fertility apps can be a helpful tool that aids an effective birth control plan.

Read more: 'I Wanted to Die': How Birth Control Pills Can Ruin Your Life

"We don't want to say, 'don't use apps,' because tech is great, but don't rely solely on apps to learn how to use the method. Use a qualified instructor to learn the method, then use the apps as an aid to help track your signs," she says. "Women are smart—they are smarter than smartphones—so I'd rather teach a woman to make those observations, those predictions, herself."

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