If you're someone who gets their periods, chances are you using a period tracker app. There are over 100s of choices to pick from on the Apple and Google app store. But some of the most popular are Flo, Eve, and Glow. But these apps may not just be tracking your cycle, but giving away your information to other companies.

Besides using period-tracking apps to monitor your cycle, you can add other details about your day. The menstruapps allow the user to the record if they had smoked, drank, had sex, were feeling depressed, etc.

In February of 2019, The Wall Street Journal reported that Flo, one of the most famous period tracking apps, had been secretly sharing its users' most personal health data with Facebook. According to the report, Flo had used Facebook's developer software to track users' data in a way that could be used for advertising purposes.

Flo had "told Facebook when a user was having her period or informed the app of an intention to get pregnant." This information would then be sent to an advertising identifier and be matched to the device or the profile of that person. Flo has taken a stance against this accusation and has said that they will stop sending this information/data to Facebook's analytic software.

Luckily, there is an online cyber-security guide designed to figure out which period app (and other apps) are the safest to use. Chupadados gives information that their consumers will need to safely navigate the world of Big Data. The Brazilian-based app found that most apps rely on the production and analysis of data for financials sustainability-meaning they make money based on their users habits that they can find from their profile. They encourage their consumers-primarily women-to learn about which apps swap their information and how they can guard their privacy.