A gynecologist's take: how you should—and shouldn't—use period tracking apps
Your period tracking app can teach you a lot about your health, but it has some serious limitations.
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Not everyone has a period. But, for those who do, a period tracking app on your smartphone seems like a great way to keep a monthly health record in the palm of your hand. These apps are a product of the burgeoning femtech industry, which, as it grows, is helping to make period tracking apps mainstream.
Even if you don’t use a period tracker (or fully understand what they do), you most likely know someone who does, or will receive a targeted ad for one in the imminent future.
What is a period tracking app?
If you search “period tracking” in an app store, at least 15 (usually monosyllabic) smartphone apps pop up, including Clue, Flo, Dot, Life, Groove, and Eve. Even mainstream fitness tracker manufacturers Fitbit and Garmin have added menstrual cycle tracking to their apps. The basic concept is simple and similar: Users enter their age, height, weight, and log basic details on each day of their cycle, with options to record sexual activity, daily mood, food cravings, exercise, and more.
Why you might use a tracking app
For someone with periods, keeping a record of menstruation is generally a useful thing to do, whether you use an app or simply record it with pen and paper. Having a historical log can help predict not only when the next period may come, but also when symptoms of PMS may rear up. It also can help approximate ovulation and the most fertile window for conception if you’re trying to increase the odds of getting pregnant.
And if there’s no consistency in the cycle, that information can be informative as well. “If someone says they’re having irregular periods, it’s good for me, as a doctor, to know what kind of irregularity they’re talking about,” Dr. Mary Jane Minkin, a clinical professor of obstetrics and gynecology at Yale Medical School, told Reviewed. This is especially true for someone who is actively trying to get pregnant, because it might help target certain fertility issues early on.
What a period tracker can’t do: diagnose fertility problems
That said, there’s only so far an app—or period tracking in general—can go. Many fertility issues can be linked to the ovaries, which are certainly a focus of period tracking apps. But other issues, such as Fallopian tube damage, will need more investigation than an app can identify. Further, the apps overlook possible male fertility problems—and, because Minkin pointed out that about “half of fertility issues are male-factor,” those issues are pretty important.
What it really can’t do: birth control
On the flipside, using an app in lieu of other forms of birth control is generally not a great idea. “It’s basically souped-up rhythm method,” Minkin said. “So a lot depends on what you can accept in terms of failure of your birth control.”
The rhythm method—also known as the “calendar method,” which aims to predict fertile days by recording the length of a menstrual cycle—is only about 76 to 88 percent effective at preventing pregnancy. Someone who really doesn’t want to get pregnant, then, is likely better served with a different form of birth control with greater efficacy rates or (of course) abstinence from heterosexual intercourse.
For what it’s worth, most period tracking apps do not position themselves as a standalone method of birth control. And they shouldn’t: A study done at University of Washington in 2017 found that period tracking apps can be unreliable for predicting future menstrual cycles, which may throw off pregnancy planning (let alone pregnancy prevention). The app Clue explains on its site why the app should not be used as a contraceptive, and Flo, Glow, and Eve don’t appear to make any statements (either way) about using them as birth control.
The main exception is Natural Cycles, a subscription-based Swedish app that prompts users to record basal body temperature, which adds another data point that improves the efficacy of the calendar method in terms of family planning. Natural Cycles was approved by the Food and Drug Administration as a method of birth control in the United States last summer. In clinical studies, the app had a 93 percent effectiveness rate. The app Dot also claims to work as birth control and lists a 95 percent effectiveness rate of preventing pregnancy, but has not been approved by the FDA. Still, Natural Cycles was reported to Swedish officials in 2018 after a hospital found that 37 out of 668 women (indeed, about 7 percent) who had sought an abortion there had been using the app as birth control. The bottom line: Apps are better used if your goal is to get pregnant than to avoid pregnancy.
Should you worry about data privacy?
Short answer: Maybe. Period tracking apps ask users for sensitive personal data, which in some instances has been stored by certain apps and shared with third parties, like advertisers and workplaces.
Ultimately, using a period tracking app can be a great way to gain a greater understanding of your reproductive health. But, as any gynecologist will tell you, it has limitations. Knowing that can help you pick which app—if any at all—is best for you.
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