On September 30, 2026, The BMJ published an analysis by Katharine Lee and colleagues arguing that digital menstrual tracking "risks creating more harm than benefit" and needs much closer scrutiny. Lee is an assistant professor in Tulane University's Department of Anthropology. The piece covers period-tracking apps, other consumer femtech tools, and "cycle syncing", the social-media practice of matching diet, exercise and lifestyle to menstrual phases. CNET puts the user base at roughly 50 million people worldwide who use apps to track cycles, symptoms, fertility and pregnancy.

Why It Matters

This is the most prominent medical-journal challenge yet to the business model of wellness-positioned cycle tracking. That model is a free or freemium app that monetises engagement, subscriptions and increasingly partnerships. Just this week Clue pointed its 100-million-user funnel at fertility insurance through Flora. The BMJ piece does not target regulated, cleared products such as fertility-awareness contraceptive apps, which carry their own clinical validation. It does give investors, clinicians and regulators a citable source for separating validated medical claims from lifestyle "syncing" content, and the line between those two is where most of the category's growth marketing sits. For the sexual-wellness side of femtech, the privacy point matters most. Cycle data is a proxy for sexual activity, pregnancy and, post-Dobbs, legal risk. Afterglow has tracked Stardust's third-party data sharing, Flo's continuing privacy disputes and INSERM's finding that most fertility apps mispredict ovulation. A BMJ-backed call for stricter data protection and clinician gatekeeping gives regulators an evidence base if they decide to move.

The evidence case is blunt. The authors say decades of sports-science research show no overall effect of menstrual phase on performance, injury risk or health, and any effects found have been "trivial and highly individualised." Research on phase-based diets to ease symptoms or improve performance is described as inconclusive or speculative. Even if such effects existed at the individual level, the authors argue that simple digital trackers could not reliably predict them. Most apps estimate ovulation, the fertile window and future phases from the user's self-reported bleeding dates rather than from any hormone measurement. "A lot of digital tracking apps are no fancier than counting and averaging your data," Lee told CNET.

The risk list goes beyond bad advice. The authors cite wasted time and labour, unwanted surveillance, threats to health-data privacy, and the possibility that trackers distract from, or even undermine, real progress in women's health. CNET adds that users may dismiss genuine symptoms as "just my cycle" or drop established diet, exercise and sleep guidance in favour of syncing. The authors recommend stronger protections for consumer and employee data, clearer disclosure of how data are used, and clinicians recommending apps only when they meet "stringent standards." They also call for regulating misleading marketing and resisting what they call the commercial co-option of feminist activist rhetoric.

Sources

Update — 2026-10-01

Initial entry — story first created.