PCOS? The Reason Your Period App Can’t Tell

Period-tracking apps Flo and Clue are catching some flack over a well-intended idea: in-app health assessments.

It’s effectively what it sounds like: the app analyzes user charts along with in-app questions and suggests a doctor’s visit if there’s reason to suspect a reproductive disorder such as polycystic ovary syndrome (PCOS).

So why are health professionals — and even some users — in such a tizzy?

Turns out, the assessments aren’t backed by any high-quality clinical studies. In other words, there’s insufficient proof that the assessments successfully identify real-life disorders.

This increases the likelihood of mis- or over-diagnosis, and even patient anxiety over a nonexistent health crisis.

Both apps claim their tests are not intended to diagnose but to alert users to health concerns, erring on the side of caution. According to the New York Times, a Flo representative tweeted: “If some [known PCOS] symptoms match [symptoms on the user charts], we encourage a user to visit a doctor just to make sure that everything is fine.”

Despite flaws in execution, the health assessment idea isn’t a bad one. Increasingly, doctors are able to identify reproductive disorders thanks to information captured by proper fertility charting.

But even if Flo and Clue had proper medical assurance that their assessments were accurate, they still wouldn’t work for a majority of period-tracking app users.

The culprit? Hormonal birth control.

One Flo user publicly complained about the shortcomings of the health assessment when it flagged her as at-risk for PCOS…based entirely on cycle changes she experienced when she began a new form of birth control.

Flo altered their algorithm to account for problems such as this, but users like @sasha_cresswell will never be able to get an accurate assessment from a tracking app.


Here’s the dirty little secret: use of hormonal contraception totally voids any charting data that could be helpful in identifying a reproductive disorder like PCOS.

Hormonal contraception necessarily manipulates the body’s natural hormonal levels in order to limit the likelihood of achieving pregnancy. Fertility charts (which are, to some degree or another, produced by these period-tracking apps) monitor those hormone levels by observing the physical changes they cause. If a woman is using hormonal birth control, none of her chart data accurately reflects the natural hormonal status of her body. Instead, the data indicates the hormone levels created by the medicine.

This is the same reason hormonal contraceptives are (too often) used to “treat” PCOS: it changes the unhealthy hormone levels and temporarily “covers” the symptoms without altering the underlying problem.

Fertility charts can be invaluable in recognizing and diagnosing reproductive disorders — but only if they reflect the hormone production of the body without extra synthetic hormones.

“Theses apps could potentially educate millions of women as to what ‘normal’ is: not every cycle is the same length, young (teenage) women and women nearing menopause have highly variable periods, etc,” says Dr. Mike Manhart, Chair of CCL’s Board of Directors. “They could also inform women if they are on hormonal contraceptives, the periods they have are driven by the drugs — not their own bodies.”

That’s unlikely to happen, though.

“[Doing so] might get more women to question why they are taking hormones in the first place,” Dr. Manhart admitted.

— Forest Barnette
Marketing and Communications Associate