The need for transparency in the promotion of popular period tracker applications (apps): a content analysis of their app store descriptions

Period tracking applications (apps) are increasingly being used by people who menstruate to predict the timing of their next period, monitor symptoms, and avoid or plan pregnancy. Despite their growing popularity, there has been a lack of critical engagement regarding their development, usage, regulation, claimed benefits, and unintended harms. This study aimed to explore how popular international period trackers are promoted, including the quality of the information provided and the communication strategies used in the app descriptions and websites. 'Period tracker' and 'Menstrual cycle calculator' were searched in the Apple and Google app stores and results were combined with Statista's report on the most downloaded period trackers and women's health apps globally. The top ten recurring apps were selected and analysed using an inductive content analysis. The content extracted was categorised into four overarching themes: (1) function and abilities, (2) marketing language, (3) health claims made, and (4) any caveats described. Most apps (60%) featured empowerment language and claimed that users would gain knowledge and understanding of their bodies (60%), yet few (40%) disclosed that they should not replace professional medical advice, diagnosis or treatment. None of the apps included a caveat that their predictions may be inaccurate and should only be interpreted as a guide. By summarising the quality of information and questioning the use of non-evidence-based claims in the promotion of period tracking apps, our findings highlight the need for greater transparency and regulation. Improving information quality, disclosing how predictions are generated, and openly communicating limitations is vital in setting realistic user expectations, enhancing menstrual health literacy, and maximising the benefits of period tracking apps for women and people who menstruate overall.