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Clue. Life. Cycles. These aren’t board games. They are just a few of the dozens of period tracker online apps that have been gaining popularity in recent years—and science has had its eye on them. Recent studies from The University of Washington and the Departments of Obstetrics and Gynecology, Weill Cornell Medical College indicate that period tracking apps provide inaccurate information. 

Dr. Robert Setton, researcher at Weill Cornell Medical, led a team of scientists who reviewed fifty-three free apps and websites designed to predict a woman’s fertile window—namely, the days of the month when she has ovulated and has the best chance of becoming pregnant. Their research showed that only three apps correctly predicted the fertile window of an average 28-day cycle: iPeriod, My Days, and Clue. But before you tap delete, it’s important to understand that these conclusions don’t paint the whole picture.

We’re Part of the Problem

The studies showed that couples should use caution if they are hoping to use an app's ovulation calculator to indicate when they could conceive or avoid pregnancy. These apps can provide a starting point for easy data entry—like when your period started or any cervical mucus you noticed—but their algorithms aren't perfect for predicting your chances of pregnancy. Most tracking apps are based on a 28-day cycle, which doesn't take into account each woman's unique cycle and needs. While the average cycle lasts twenty-eight days, this only represents about 13 percent of cycles.

Dr. Marguerite Duane, MD, MHA, FAAFP, family physician and the Executive Director of Fertility Appreciation Collaborative to Teach the Science (FACTS) tells Verily, "I would not necessarily say that women are using the apps wrong, but rather they may be placing too much confidence in them. Cycle tracking apps are tools that women can use to facilitate monitoring their cycles, including observations of their signs of fertility. Like many tools, women need to understand the capability and learn how to use it appropriately, otherwise it may not be helpful at all and could potentially cause more harm than good."

The App Is a Car, and You’re the Driver

Dr. Duane uses the analogy of a car to explain the best use of period tracking apps: A car can make it easier to get from point A to point B, but you need to attend driving school, practice, and take tests before you can get your license. "The last thing we want to see is for people who have never learned how to drive to sit down behind the wheel of a car and take off," Dr. Duane says. "Likewise, it would be equally as dangerous for a woman who has never learned about how to chart her cycle to simply download an app and start tracking when she does not have the background knowledge or in-depth understanding about the nature of her reproductive cycle."

Anna Halpine, founder of the Fertility Education & Medical Management program (FEMM) says, "It is not enough to know what you are observing on a particular day (bleeding, dryness, moisture, etc.)—women also need to understand how to make sense of the broader patterns that this generates for them." Halpine adds, "These patterns are powerful tools in providing health and fertility snapshots to women at a glance."

Dr. Duane says most apps can't teach you the nuances of FABMs or help you truly understand your health. "[A]s Anna noted, even though many apps encourage or allow women to enter observations like cervical fluid or basal body temperature, most of them still simply predict fertility based on calendar algorithms." If women don't have a good understanding of FABMs and what the fertility signs they're tracking even mean, "they may not realize that the app is not well-suited for their goals," says Dr. Duane.

The Right Way to Use Cycle Tracking Apps

The best way to use a cycle tracking app is to use it in conjunction with learning a fertility awareness-based method (FABMs) from a trained instructor. "[A]n app is only as good as the user’s input," says Dr. Duane. "Therefore, it is important that women learn how to accurately observe their signs of fertility so that they can enter the information correctly into the app." Then you can share the data in your period tracker with your doctor who can provide a more thorough report of your health

It isn't just about the technology. A good tracking app should also get you "linked into a community of support, health coaching, and medical providers able and ready to assist you as your needs unfold," Halpine notes.

Ultimately, Trust Yourself—Not Your App—to Predict an Accurate Fertile Window

After learning a FABM, Dr. Duane encourages women to trust themselves and the knowledge they've gained, "It typically takes most women about three months to learn how to track their cycle with confidence. If they are ever in doubt, whether it is uncertainty about an observation or the app-predicted fertile window does not match their own prediction, then it is useful for them to reconnect with the teacher that they learned from initially so they may gain clarity and improved confidence in their skills."

It's an exciting period of history for tech in women's health, and we hope better app design is in the works. Until then, let's not be so quick to ditch our cycle trackers, but change how we depend on them instead.

"I believe women are smart and, in fact, smarter than their smartphones," Dr. Duane says. "We simply need to take the time to teach them and instill in them the confidence to understand their fertility, and, if they desire, use an app to simply help them track their signs."

Read Next: The Most Accurate Apps for Charting Your Cycle

Photo Credit: Marc Andre Julien