Apple Stands to Revolutionize Period Tracking — If It Doesn’t Mess Up

A lot is riding on how much the company is willing to share with the public

Erin Schumaker
Published in
4 min readJun 5, 2019


DDr. Sumbul Desai, vice president of health at Apple, was met with cheers on Monday during the company’s Worldwide Developers Conference when she announced the tech giant had created a service specifically for monitoring menstrual cycles.

“This one is for you,” Desai said, addressing the women in the crowd. “Cycle Tracking.”

“Knowing more about your menstrual cycle gives you a window into your health, from simply ensuring you’re prepared to understanding your personal patterns and regularities,” she added.

For now, the service is available only to developers, but it’s scheduled for a full consumer release with watchOS 6 this fall. Apple Watch and Apple Health app users will then have the option of inputting data about their menstrual cycle history, such as the date of their last period, length of cycle, and symptoms. The service will use this information to make period cycle and “fertile window” predictions for the user.

“We have very limited information about how Apple intends to proceed.”

Those cycle predictions will alert women when their period is about to start. Fertile window predictions will tell women, based on their health data, which six days in a month they’re most likely to be fertile. (A footnote in Apple’s watchOS 6 press release notes “fertile window predictions” — otherwise known as the rhythm method — “should not be used as a form of birth control.”)

“We are so excited to bring more focus to this incredibly important aspect of women’s health,” Desai said at WWDC.

But not everyone is sold on Apple’s entry into reproductive health.

“We have very limited information about how Apple intends to proceed,” says Chelsea Polis, a senior research scientist at the Guttmacher Institute, a nonprofit research group that focuses on reproductive health. Polis notes it’s difficult to understand how accurate Apple’s Cycle Tracking app is without understanding the algorithm the tech company is using to predict upcoming periods and fertile…