These FemTech thinkers are helping women take control of their sexual and reproductive health, one period at a time.

Mellor (right), a Fitbit engineering manager, remembers a time when she tracked her period using the ancient technologies known as pen and paper. Her colleague Lafon, a senior research algorithm scientist, didn’t spend much time thinking about her period at all.

“As educated as I am,” says Lafon (she has a master’s in physics and a PhD in biomedical engineering-NBD!), “I didn’t know much about my cycle.” Now, she does-thanks to work she and Mellor did to develop Fitbit’s newest feature: a female health tracker built into the app (it debuted in the Versa smart watch) that lets users log periods and symptoms to help them predict future timing, identify their estimated fertile windows, and see patterns during their cycles.

The collab deets: Lafon spent hours reading studies and liaising with medical experts to help convince execs that the feature deserved the green light. Once the project ramped up, Mellor led the engineering team in charge of coding and building the product.

“Information really is power,” Mellor says. The truth is, it has to be the right info designed in the right way. This doesn’t always happen because a lot of tech is developed by men. “One way we can help women connect with products is by showing them more things built by women, for women,” says Mellor.

To date, 4.5 million Fitbit users have added the period-tracking app-and more than 8 million periods have been logged. Mission accomplished!

This article originally appeared in the October 2018 issue of Women's Health. For more great advice, pick up a copy of the issue on newsstands now!