Menstrual Tracking Apps Collecting Personal Data Which Can Be ‘Sold at Scale’: Report

Researchers said the way data are currently handled presents a ‘frightening’ privacy risk for women.

File photo of a woman using her mobile phone on May 8, 2019. Yui Mok/PA Wire

Researchers at the University of Cambridge have said that period-tracking apps on women’s smartphones may be collecting their personal data which can be “sold at scale” and used for targeted advertising.

Cambridge’s Minderoo Centre for Technology and Democracy said in its report published on Wednesday that like other forms of health data, cycle tracking app (CTA) data are a “veritable gold mine for consumer profiling” because of the insights they provide.

CTAs give women a centralised place to track daily indicators related to their menstrual cycles and offers predictions on when their periods are due and when they are likely to be at their most fertile. They are also used by women who have irregular periods or conditions like poly-cystic ovary syndrome or endometriosis, and want to keep track of their cycle and symptoms.

Report authors explained that most cycle tracking apps are targeted at women trying to get pregnant, which is one of two life events linked to dramatic shifts in consumer behaviour (the other being the purchase of a house).

“Data on who is pregnant, and who wants to be, has therefore emerged as some of the most sought-after information in digital advertising for over a decade,” they said.

Researchers said that data on pregnancy are believed to be 200 times more valuable for targeted advertising than other forms of data, including age, sex, and location.

“The use of cycle tracking apps is at an all-time high,” said Professor Gina Neff, executive director of the Minderoo centre, adding, “Women deserve better than to have their menstrual tracking data treated as consumer data.”

Cycle-Based Advertising

The academics cited research on hormonal influences of consumer behaviour, in particular the theory of “cycle-based advertising” which seeks to target advertisements to women based on the phase of their menstrual cycle.

They wrote that the approach suggests fluctuations in hormones can influence a woman’s susceptibility to different services and products, which would allow for more precise and targeted marketing.

Authors highlighted how this data could be used, explaining: “In cycle-based advertising, the first half of the cycle, dominated by oestrogen, is referred to as the ‘mating phase’ and advertisements may advertise products like revealing clothing and cosmetics.

“The second half, influenced by progesterone, is called ‘nesting’ and ads shift to home goods or plants.”

Researchers said the way data are currently handled presents a “frightening” privacy risk for women.

The report’s lead author, Stefanie Felsberger, said, “Menstrual cycle tracking apps are presented as empowering women and addressing the gender health gap.”

She added, “Yet the business model behind their services rests on commercial use, selling user data and insights to third parties for profit.”

Clearer Opt-Outs

The Minderoo centre has said CTA app companies should supply users with clearer information on how their data will be tracked, including options for those who aren’t using the tools to plan a pregnancy.

There should also be meaningful data-sharing consent permissions, and users should not be presented with “all-or-nothing” consent options.

Feltsberger said that at the very least, commercial apps should include delete buttons, so users can erase their data from the app and the company’s servers.

An undated file photo of a pregnant woman. PA

Research jointly conducted last year by King’s College London and University College London found that women’s health and fertility tracking apps were exposing users to unnecessary privacy risks “through their poor data handling practices.”

“Many of the pregnancy-tracking apps had a requirement for users to indicate whether they have previously miscarried or had an abortion, and some apps lacked data deletion functions, or made it difficult to remove data once entered,” they found.

ICO Investigation

In 2023, the Information Commissioner’s Office (ICO) began a review into period and fertility tracking apps, after a poll commissioned by the regulator found that half of women who used them expressed concern over transparency.

The research also found that over half of those who used CTAs believed they had noticed an increase in fertility or baby-related advertisements since they signed up for the apps.

In February 2024, the ICO said that “no serious compliance issues or evidence of harms were identified” in their review.

Emily Keaney, the ICO’s deputy commissioner of regulatory policy, said at the time: “We want to reassure users that we haven’t found any evidence these apps are using their data in a way that could cause them harm.

“However, our review has highlighted there are improvements app developers could make to ensure they are meeting all their obligations to be transparent with their users and keep their data safe.”

This includes telling people how they will be processing their personal data, retention periods for that data, and who it will be shared with.

They must also obtain “valid consent” on how they will use women’s data, with the ICO saying obtaining consent “must be explicit, unambiguous and involve a clear action to opt-in.”