In the field of sexuality and women's health, a growing number of applications are presented by their designer as birth control devices, where women can enter data about their menstrual cycles. No less than 250 period tracking apps are available in Google's Play Store. Studying these apps is nowadays crucial : after 2012 – 2013 controversies related to the health risks associated with 3rd and 4th generation pills, the lost of trust in the pill seems to be a motivation for women to start using these apps as a way to better understand – and control – their body. Chemical hormones are being abandoned by several women in favor of other technologies. For example, Natural Cycle is a period tracking app that claims to be “as effective as the pill but using only mathematics”. Does data-science appear « more reliable » or « more natural » for users, compared to pharmaceutical science ? However, these apps harvest heterogeneous data which can be medical, social, physiological, psychological, sexual or linked to daily lifestyle. Indeed, the intimate data of users are at the heart of those apps' business model and their design encourages users to fill in as much data as possible, as frequently as possible. In addition to privacy and data security risks, in the US, several apps have been accused of sharing users' health data with social media, insurers and employers. With the recent threats on abortion rights, many activists have been calling on women to remove these apps from their smartphones. Nevertheless, women explain that they still use these apps because they benefit from dashboards and advice, and use them to make sense of their body, to make choices about their fertility, sexuality and health, and to organize their daily life. As data are at the heart of both economic processes (for companies) and sense making process (for women), how does a digital technology based on the collection and visualization of intimate data shape the gendered body experience of users?