More and more women use a period tracker: an app that keeps track of your menstrual cycle. These apps do not always treat the intimate data you share with them carefully.

An app that notifies you when to expect your period or when you are fertile can be useful, for example to predict when you can expect to suffer the side effects that for a lot of women come with being on your period. In itself, keeping track of your cycle is nothing new: putting marks in your diary or on your calendar have always been an easy way to take your cycle into account. But sharing data on the workings of your body with an app is more risky.

'Magic Teen Girl Period Tracker'

There seems to be quite a large market for period tracker apps. From ‘Ladytimer Maandstonden Cyclus Kalender’ to ‘Magic Teen Girl Period Tracker’, from ‘Vrouwenkalender’ ('Woman calendar') to ‘Flo’. They are neatly lined up in different shades of pink in the appstore. 'Femtech' is seen as a growing marketRead more about the 'Femtech' market that has raised a billion dollars in investments over the last couple of years by different startups. Are these apps made to provide women with more insight into the workings of their bodies? Or to monetize that need?'period tracking apps are not for women'

It’s interesting to look at what kind of data these apps gather. The app usually opens with a calendar overview. In the overview you can input the date of your last period. In addition, you can keep a daily record of how you feel (happy, unhappy, annoyed) and whether you experience blood loss. But for most of these apps it doesn't end there. Have you had sex? ('Did you get some?') And if so, with or without protection? With yourself or with another person? How would you grade the orgasm? Did you have a stomach ache? Were your bowel movements normal? Did you feel like having sex? Sensitive breasts? An acne problem? Did you drink alcohol? Exercise? Did you eat healthy?

For a number of these questions it is understandable why answering them might be useful if the app wants to learn to predict in what stage of your cycle you are. But a lot of these questions are quite intimate. And all this intimate data often seems to end up in possession of the company behind the app.

What is in the privacy statements?

The logical question then is what exactly a company does with all this data you hand over. Do you have any say in that? Do they treat it carefully? Is the data shared with other parties?

After digging through a number of privacy statements it appears that one of the most used apps in the Netherlands, 'Menstruatie Kalender' ('Menstrual Calendar'), gives Facebook permission to show in-app advertisements. It is not clear what information Facebook gathers about you from the app in order to show you advertisements. For example, does Facebook get information on when you are having your period?

Another frequently used app in the Netherlands is Clue. It is the only one we encounter with a comprehensive and easily readable privacy statement. You can use the app without creating an account in which case data is solely stored locally on your phone. If you do choose to create an account you give explicit consent to share your data with the company. In that case it is stored on secure servers. With your consent it will also be used for academic research into women's health.

This can not be said of many other apps. Their privacy statements are often long and difficult to read, requiring good reading-between-the-lines skills to understand that data is being shared with 'partners'. It is possible that the sensitiveness of your breasts in itself is not very interesting to an advertiser, but by keeping track of your cycle the apps automatically acquire information on the possible start of one of the most interesting periods of your life for marketeers: motherhood.Motherhood marketing, it's a thing

Fertility marketing

The most extreme example is Glow, the company behind the 'period tracker' app Eve. Their app is focused on the potential desire to have children. The company's tagline is as straightforward as they come: 'Women are 40% more likely to conceive when using Glow as a fertility tracker.' Besides Eve, Glow has three more apps: an ovulation and fertility tracker, a baby tracker and a pregnancy tracker. The apps link to the Glow-community, a network of forums where hundreds of women share their experiences and give each other tips.

But that is not the only thing that Glow offers. You can not use a Glow webpage or app without being shown the 'Fertility Program'. For 1200-7000 Euros you can enroll in different fertility programs. Too expensive? You are able to take out a cheap loan through a partnership with a bank. And in the end, freezing your eggs if you are in your early thirties is the most economically viable option, according to the website.Tips from Glow about eggfreezing

Turns out, Glow is a company selling fertility products that has built a number of apps to subtly (and sometimes not so subtly) attract more female customers. As a consumer you think you are using a useful app for keeping track of your cycle, but in the meantime you are constantly notified of all the possibilities of freezing your eggs, the costs of pregnancy at a higher age and your limited fertile years. Before you know it, you are lying awake at age 30, wondering whether it would be more 'economical' to freeze your eggs.

What happens with your data?

These apps shed light on what seems to be a contract we are forced to consent to more and more often. In exchange for the use of an app that makes our lives a little bit easier, we have to give away a lot of personal information without knowing exactly what happens with that information. The facts that these apps deal in intimate information does not mean that the creators treat it more carefully. To the contrary: it increases the data's market value.

So think again before you download one of these apps, or advise your daughter to download one. Take your time to read an app's privacy statement so you know exactly what the company does with your data. But there is also a responsibility for the regulatory body, such as the Autoriteit Persoonsgegevens in the Netherlands, to ensure companies don't abuse your intimate data.

Are you using one of these apps and do you want to know which data the company has gathered on you, or do you want to have that data erased? You can easily draw up a request which you can send by mail or email using My Data Done Right.

This article was translated from Dutch by Bits of Freedom-volunteer Axel Leering.