As part of the review, the ICO said it wanted period or fertility tracker app users to share their experiences in a call for evidence and added it would also contact companies providing the apps to find out how they process personal information.

A focus of the ICO’s work will be to identify whether there is the potential for harm and negative impact on users, which could include unnecessarily complicated and confusing privacy policies, apps requesting or storing unnecessary volumes of data or users receiving upsetting targeted advertising.

The ICO will also commission focus groups and user testing as well as working with key stakeholders, including women’s health groups.

The review follows the publication of findings from a poll commissioned by the ICO in to women’s concerns on data security on period and fertility trackers, with 59% saying transparency over data use and 57% saying security of the app were concerns over using the apps.

In contrast, cost and ease of use were both concerns among 55% of respondents, with the ICO poll suggesting a third of women have used apps to track periods or fertility.

The research also showed over half of people who use the apps believed they had noticed an increase in baby or fertility-related adverts since signing up. While some found the adverts positive, 17% described receiving these adverts as distressing.

Emily Keaney, deputy commissioner of regulatory policy at the ICO, said: “We want to make sure women can use these services with confidence, so we’re calling for people to share their experiences.

“This will help us understand whether there are areas that need improvement – from how easy it is to navigate privacy policies to whether people have experienced upsetting and unexpected targeted advertising. We also know some users feel these apps bring many benefits and we’d like to hear about these too.

“As with all health apps, we would expect organisations to safeguard their users’ privacy and have transparent policies in place. This review is intended to establish both the good and bad of how the apps are working currently.”