Berlin-based Clue, which helps women track their menstrual and fertility cycles, has secured $7 million in Series A funding from investors including an early backer of Twitter and SoundCloud.

New-York based Union Square Ventures LLC and London’s Mosaic Ventures are leading the round, which will help the popular app/service maker add new product features, hire staff, further push growth and enter more markets.

“Clue has cracked the code of how to get women to understand and share data about their well-being and at the same time create value for every user,” said Albert Wenger, a partner at Union Square. “It has the network effect: As you have more users, the service gets more valuable.”

The Clue app lets women enter data such as moods, body temperature and sexual activity to analyze and predict their period, fertile windows and premenstrual syndrome.

Women’s health apps are the second-largest market in the health and fitness category by downloads after running apps. Clue’s competitors include San Francisco-based Glow, which itself doesn’t lack neither capital nor users.

However, Clue is the “fastest-growing app in its category,” and has the potential to reach “hundreds of millions” of users, according to Simon Levene, a ‎co-founder of Mosaic Ventures. It could make money by linking users with medical professionals or offering them individualized services and products, he said.

Other investors in the company include Groupe Arnault SAS and Brigitte Mohn, a member of the family that controls German media group Bertelsmann.

[Via: Bloomberg]