The App That’s Quietly Changing Women’s Health Around the World

Sponsored by Clue

For generations, women have been expected to navigate their reproductive health with little more than guesswork and outdated tools. That’s exactly what drove Ida Tin to launch Clue, a period tracking app built not just for convenience, but for clarity, empowerment, and long-overdue innovation. In a recent conversation on With Whit with Whitney Port, the Clue founder opened up about her journey from frustrated user to femtech pioneer, sharing how a single Post-it note in her Copenhagen apartment sparked a global movement. From building the world’s largest menstrual health dataset to leading the charge for ethical data protection in a post-Roe v. Wade world, Tin makes a compelling case for why cycle tracking isn’t just helpful—it’s essential.

How Ida Tin of Clue App Built the World’s Largest Period Dataset

The frustration that launched a femtech revolution

Before Clue became one of the most trusted names in period tracking, it began with a question that frustrated Tin personally: Why has there been virtually no innovation in family planning methods since the birth control pill in the 1950s? “I was like, wow, we have put people on the moon since then, invented the internet and so many other things,” she tells Port. 

Fed up with hormonal birth control methods that negatively impacted her mood and energy, Tin started imagining a future where women could find out, with confidence, whether they could get pregnant that day. “That was really the beginning,” she says. “Honestly that question also kind of made me a little bit like, wait, what? How can this not have been a super important thing for human mankind?”

Without a smartphone—or even the money to buy one—she taped a Post-it note to her wall that read “Ida – Vision Holder” and began mapping out an imaginary team that could help bring her idea to life. She initially set out to build a hardware device that analyzed saliva for hormonal changes, but it was her co-founder who suggested starting with a period tracking app. That pivot laid the groundwork for what would become Clue. 

Beyond a calendar app

When Clue first launched, most period tracking apps were nothing more than digital calendars. Tin and her team wanted to change that. “We were building the period tracking app and what we learned was that when you collect data on women’s cycles, you can actually help people with all kinds of things,” she explains. “You can help them not get pregnant. Maybe you can help them get pregnant. But you can also help them understand how this whole cycle works.”

What started as a way to answer a simple fertility question quickly evolved into a larger mission: to make cycles measurable and actionable. Clue helps users understand patterns tied to mental health, sexual energy, muscle building, and more—all rooted in science rather than assumptions. “It’s related to our sexuality and our mental health and our energy levels and how we build muscles and all kind of really interesting things,” Tin says.

And it’s not just about individual insight. The app’s expansive, diverse dataset has captured the attention of researchers around the world. “There had never been a data set of this magnitude about women’s science before,” she says, noting that Clue’s user base extends far beyond the limited scope of traditional clinical trials. “Not just white college students in America, but actually a global data set.”

Data privacy in femtech

As period tracking apps have become more popular, concerns about data privacy have grown. For Tin, she wanted to build Clue ethically. “Of course, you have to honor people’s trust,” she says. “Because without people’s trust, why would anybody use your product?”

Clue’s Berlin headquarters subjects the company to Europe’s strict data protection regulations, something Tin sees as a strength rather than a limitation. “Everybody’s data, no matter where you use the app, is based and stored and treated under European regulation,” she explains. This means Clue has never—and will never—disclose users’ private health data to authorities, no matter what country they live in.

Tin also stressed that who builds femtech matters, especially when many companies rely on data monetization to grow. “It’s not just what founders choose to do. It’s also what pressure they’re under from their investors,” she reveals. Instead, Clue is built on a transparent, subscription-based model. “If people don’t understand how you make money, it’s usually because users would be uncomfortable if they knew.”

Cycle tracking is an important record of your health

While many people consider period tracking as simple calendar marking until their next cycle, Tin advocates for understanding it as something more powerful. “Women can only participate really fully in society if they feel well in their bodies,” she explains, “and it’s a help to feel well if you understand what’s going on.” 

Tracking your cycle can offer insights into mood, energy levels, and early signs of health issues. “It is almost like a navigation,” Tin says. “As you start being able to read the signs of your body, you understand what’s going on, and you can better navigate your life.” 

Even for Port, the app has changed how she relates to herself emotionally and physically. “Just the fact that I can see where I’m at in my cycle…I can honor that and maybe be easier on myself,” she shares. Tin echoes that sentiment: “It’s not about this chore, but rather this, wow, this is a really interesting data set and it’s really enabling my life, my health journey.”

How Clue users are powering research that matters

With more than 30 billion health data points collected from users in 190 countries, Clue has created the world’s largest menstrual health dataset and has partnered with researchers at Stanford, Columbia, and Oxford, among other institutions. “People come with so many great questions,” Tin says.

One such study with MIT revealed that air pollution affects menstrual cycles. Another study with Stanford uncovered that many adolescent girls experience extremely heavy bleeding—a pattern that had previous gone under-researched.

The app has become a vital tool for scientific discovery, with more than 6.9 million Clue users participating in research studies and 85% of surveyed members indicating they want their de-identified data used for research. “It’s almost like this physical sensation of when people enter a data point, they’re like pushing female health research,” Tin says.

What your cycle can tell you, and why you should start tracking

For anyone considering cycle tracking but unsure where to begin, Tin’s advice is simple: “Lead with curiosity.” It shouldn’t feel like work. “Try for a few months, see if it makes you curious about learning even more,” she says, noting that Clue offers “scientifically super solid and fact-checked” content to guide users.

Beyond knowing when your period is coming, tracking your cycle can reveal how your body changes across the month—and throughout your life. “A lot of people think that there’s only the period going on,” Tin says, but “you have these hormonal shifts that make an egg release…and it influences our social patterns, how our vision works, how we build muscle tissue, our vocal cords.”

As Tin enters perimenopause herself, she’s noticed how her cycle used to serve as a guide. “Suddenly it’s like this sense of navigation I’ve had in my life for so long—I’m like lost,” she says. “That really tells me how much it was a navigation while I had my regular periods.”

Whether you’re managing symptoms, navigating fertility, or wanting  to feel more in tune with your body, Tin believes the right tech should feel like “your best ally.” Her advice? “If your technology doesn’t feel like it’s empowering, find something else…it should feel like it’s got your back.”

To learn more and get started, use code WITHWHIT at checkout on helloclue.com for 90 percent off your annual Clue subscription.