The Clair wearable’s rose-gold housing and soft band lean more jewelry than fitness tracker—part of the company’s pitch that hormone monitoring deserves its own design language.
Clair Health was co-founded by Stanford graduates Jenny Duan and Abhinav Agarwal and is building a noninvasive, continuous hormone-monitoring wearable for women, with a wrist-worn device and app launching in November 2026.
Jenny Duan spent months logging her cycle into a period-tracking app, hoping the data would eventually tell her something useful. It never did. Her cycle was irregular, the app’s predictions kept missing, and the gap between what her body was doing and what the app understood about it never closed.
That frustration is now a funded company. Clair Health, the startup founded by two Stanford graduates Duan and Abhinav Agarwal, has closed $11.6 million led by Khosla Ventures, with a16z speedrun, Anne Wojcicki and a roster of health-focused investors joining in. The company says more than 25,000 people have joined its waitlist ahead of a November 2026 launch.
But Clair’s wearable doesn’t measure hormones directly. It infers them—from skin temperature, heart rate, sleep and breathing data—using machine learning models trained to spot hormonal patterns inside signals wearables already collect. That distinction is the most interesting thing about the company, and the riskiest.
The Cycle App That Told Her Nothing
Jenny Duan, the 22-year-old co-founder and CEO of Clair Health, which raised $11.6 million this month to build a continuous hormone-monitoring wearable.
Clair Health was co-founded by Stanford graduates Jenny Duan and Abhinav Agarwal and is building a noninvasive, continuous hormone-monitoring wearable for women, with a wrist-worn device and app launching in November 2026.
Duan’s path to Clair started before Stanford. In high school, she worked with women experiencing domestic violence and homelessness through a nonprofit in Oregon, where she repeatedly watched healthcare providers dismiss women’s symptoms for lack of quantitative data
That experience stayed with her. At Stanford, where she studied symbolic systems with a focus on AI ethics, she met Agarwal, who had a background in wearable hardware and algorithms. The two kept circling the same idea: wearables had been collecting heart rate, temperature and HRV data for years, but nothing was reading those signals through the lens of hormones..
Her own irregular cycle wasn’t an edge case. The company puts the number at 30% of women—a population large enough that “calendar-based predictions and population averages” amount to a coin flip for nearly a third of the people relying on them.
A Wearable That Guesses, Not Measures
Here’s what Clair actually is: a jewelry-style wrist device packed with 10 biosensors, paired with an app that runs 130-plus proprietary biomarkers through models trained to estimate levels of estrogen, progesterone, LH and FSH. No blood draws, no urine tests, no needles.
The wrist was a deliberate choice over a finger. Running 130-plus biomarkers through 10 biosensors continuously requires more battery and component capacity than ring-sized hardware can support—the wrist is the smallest form factor that can sustain that load all day, every day.
In beta testing, the company says it has identified nine distinct sub-phases of the female hormone cycle—more than double the four phases most women have never been taught.. It’s a genuinely interesting claim, and if it holds up, it could reshape how cycle-related symptoms get explained to patients.
But “identified” and “measured” are doing very different jobs in that sentence. Clair’s models are inferring hormonal activity from proxies—the same kind of data Oura and WHOOP already collect for sleep and recovery scores. That’s not a flaw so much as the entire bet: continuous glucose monitors don’t measure blood glucose directly either, and they still transformed diabetes care.
The question Clair will have to answer, repeatedly, is what happens when the inference is wrong. A missed workout recommendation is low stakes. A wrong signal about ovulation timing or a perimenopause transition is not—and the company’s own framing, that this is a wellness device rather than a diagnostic one, will get tested the moment 25,000 waitlisted users start making real decisions based on what their wrist tells them.
Why Oura And Whoop Didn’t Build This First
Clair’s pitch leans hard on a structural argument: the wearable giants built their platforms around 28-day cycle assumptions or male physiology, then bolted on women’s health features later. WHOOP, Oura and Fitbit have all expanded in this direction—but in Clair’s framing, hormone monitoring is still a feature sitting on top of someone else’s architecture, not the foundation underneath it.
That’s a fair description of how the category evolved, and it’s also a competitive opening rather than an empty field. Eli Health is pursuing hormone insight through at-home saliva testing, and Inne has already secured regulatory approval in the UK and EU for a saliva-based hormone monitor used for contraception. Both take a more direct measurement approach than Clair’s wrist-based inference—slower, more clinical, but closer to ground truth.
Clair’s wager is that convenience wins: a wearable people already put on every day beats a saliva cartridge, even if the wearable is guessing. Whether that wager pays off depends entirely on how good the guess is.
The Money Behind The Bet
“Clair represents a generational shift in women’s health, moving from guesswork and episodic testing to continuous, real time hormone intelligence that can inform daily decisions,” notes Emily Bennett, Partner at a16z speedrun. “At a16z speedrun, we’re excited to back Jenny and Abhinav as they build the system to make one of the most foundational biological signals measurable and actionable, unlocking a future where women’s health is proactive, deeply personalized, and truly data-driven.”
Bennett’s framing—that this is a generational shift—is the kind of line that’s easy to nod along to and harder to interrogate. Women’s health funding has surged since 2022, and “underfunded and underresearched,” the same phrase the press release uses to describe the broader category, has become almost as common in pitch decks as it is in research papers. That doesn’t make the framing wrong. It does make it worth asking whether Clair represents a shift in what’s possible, or simply a shift in what investors are now willing to fund.
“As a sports medicine physician and scientist focused on female athlete health, I see a major need for better tools that help women understand how hormonal patterns may relate to training, recovery, symptoms, and performance across the lifespan,” explains Dr. Emily Kraus, a Clair Health advisor. “Clair Health is building toward a more personalized and data-informed future for women’s health… That would be a major win for women, not only in sport, but across every stage of life.”
Kraus’s perspective matters because she’s the kind of person who will be asked, professionally, whether Clair’s inferences are clinically meaningful—not just whether the product is well-designed. Her framing, “across the lifespan,” is also a useful gut check: Clair’s founders are 21 and 24, building toward a perimenopause use case neither has lived through yet.
The Real Test Starts In November
Clair says it’s launching an independent clinical trial through Stanford’s Gladstone BeeHive program, with peer-reviewed publication of results—a step the company frames as proof that its science should be checked by people other than itself..
That trial, more than the funding round, is the thing to watch. $11.6 million buys a launch. It doesn’t buy validation. Between now and November, Clair has to prove that a wrist can do what it took medicine decades to admit women’s bodies needed in the first place—pay attention.