Cycle-tracking apps may do more harm than good, according to a new analysis published in the peer-reviewed medical journal The BMJ. An estimated 50 million people worldwide use apps to monitor their menstrual cycles, along with associated mental and physical symptoms, fertility and pregnancy, yet the authors argue the risks attached to these tools across the femtech market outweigh their benefits.
The concerns also extend to digital tools that promote cycle syncing, the practice of basing diet, exercise and other lifestyle habits on the different phases of the menstrual cycle. Katharine Lee, one of the article’s authors and an assistant professor in Tulane University’s Department of Anthropology, said she hopes people understand that many of the big claims around cycle tracking and cycle syncing encountered on social media or in fitness and wellness spaces are not based on scientific evidence.
The health risks
Drawing on several studies, the analysis states that sports science research has shown there is no reliable way to generalise about how different menstrual cycle phases affect health, performance or injury risk. These correlations are highly individual. Research on how diet can reduce cycle symptoms or improve performance is similarly described as inconclusive or speculative.
Even if such connections existed, the article argues that digital tracking tools would be unable to predict them. Apps tend to rely on a user’s self-reported menstrual bleeding date to estimate ovulation, the fertile window and future cycle phases. Without measuring hormones directly, these estimates can be imprecise, particularly because hormones and ovulation fluctuate. The tools also cannot diagnose menstrual disorders or identify the causes of painful periods.
Lee advised working with trusted health professionals when concerns arise, while acknowledging that many people struggle to get their doctors to listen about their periods. She noted that many digital tracking apps are no more sophisticated than counting and averaging a user’s data. There is also a risk that users may downplay genuine health concerns as mere effects of their cycle, or abandon established diet, exercise and sleep guidelines in the name of cycle syncing.
The privacy problem
Privacy is a further consideration. Some apps permit third-party tracking, fail to publish transparency reports, do not allow straightforward data deletion and do not use local data storage. These factors make it easier for data to be sold, shared with third parties or exposed in a breach. The analysis highlights that this is especially dangerous in areas where abortion is criminalised or where there is greater gender or sex-based discrimination.
No specific apps or tools were named in the analysis, though Lee said several of the cited references focus on the policies or functionality of particular products. The article was published in The BMJ on a Wednesday.
