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Excited to share Clair and its cycle tracking technology this week. The team is fresh out of a16z Speedrun, building one of the most precise hormonal tracking wearables out there.
See you soon!
Clair is working on a noninvasive wearable wristband designed specifically around female hormonal physiology. It tracks hormones like progesterone, estrogen, luteinizing hormone, and follicle-stimulating hormone by reading their unique physiological signature in women’s bodies. To do that, it captures over 130 biomarkers with a stack of 10 biosensors, some of which no other consumer wearable has, per Clair.
Together, they read signals like skin temperature, heart rate variability (small changes in the time between heartbeats), electrodermal activity (tiny changes in skin sweat that show how your nervous system reacts), and more. In addition to hormone tracking, it captures sleep, recovery, and daily activity around these hormones. Then, its AI compares these signals with lab results from other women to show where a woman is in her hormonal cycle. As a consequence, it offers much more precise insights than regular wearables do.
Clair aims to offer a complete reading of the different hormonal phases of women's lives. This would be an all-in-one solution that helps women understand their own bodies better, offering clarity in areas such as training and recovery in sports, fertility planning, and phases such as perimenopause and menopause.
Check it out: wearclair.com
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Clair launches as a wellness product in November 2026, priced at $369. The device is available for pre-order today, shipping to the U.S. in December 2026 and to the U.K., Spain, Brazil, Australia, and New Zealand in mid 2027.
Founding Members get 20% off (paying $295) the price of the device plus six months of the Clair Pro app subscription for free (then $9.99 per month for Pro or $5.99 per month Core), local community events, and office hours with the Clair team.
The company affirms it’s 100% refundable until shipment, plus a six month satisfaction guarantee after delivery. It’s also HSA/FSA eligible.
Raised an oversubscribed $11.6 million seed round in June 2026 led by Khosla Ventures with contribution from a16z Speedrun, Brydge Club, Treehub, Cartan Capital, AGI House, Insiders VC, and Anne Wojcicki (co-Founder and CEO of 23andMe)
Has a 25,000 person waitlist, sold out its presale with 5,000 Founding Members, and received more than 100 LOIs from fertility clinics
Partnered with Mayo Clinic Platform, which gives it access to its medical experts and millions of anonymous patient records to help prove its technology works
Correctly identified which phase of the menstrual cycle a woman was in 94% of the time, benchmarked against daily urine samples, the same standard as at-home ovulation strips
Clair is hiring across engineering, operations, clinical, and creative roles. Check here for more information.
I was logging data month over month, but nothing changed — and it was a big struggle for me to understand how my hormones were changing and how I could adjust my lifestyle.”
Jenny Duan spent months logging her cycle into a period-tracking app, hoping the data would tell her something useful about her irregular cycle.
It never did.
That frustration connected with an earlier experience. Duan had become interested in women's health while working at a nonprofit in Oregon with women facing domestic violence and homelessness during high school. There, she saw how these women faced enormous problems with healthcare providers because they had no concrete data about their own health.
At Stanford, she met Abhinav Agarwal on a spring break trip organized by the university. The two clicked right away. Their backgrounds complemented each other, too. Duan brought her experience in women's health, while Agarwal had worked at Kos, a startup building a noninvasive glucose monitor called Argus.
Together, she and Agarwal spotted a gap composed of two problems.
First, wearables were already collecting body signals but no one had built the algorithms to read hormonal patterns from them. Today, this information is collected, but it’s scattered across different tools, like an app to track periods, at-home urine sticks for analyzing hormones, and a fitness wearable like WHOOP for everything else. There’s no centralized place where that data gets unified to discover and share insights about women’s hormonal health.
Second, even when collecting all this data, most of these tools don't take into account, by default, that women's hormones change throughout the month, something essential for understanding the female body and giving women true insights about their bodies.
That's the missing piece the duo identified. Now, they’re addressing it with Clair, affirming it’s the world’s first noninvasive, real-time hormone tracker for women.
Women make up half of the world’s population, yet it was only in 1993 that the National Institutes of Health started requiring women to be included in clinical trials.
Yes, that's just 33 years ago.
According to the Association of American Medical Colleges, some researchers even avoided using female mice because buying and housing both sexes cost more, and they worried that female hormones and reproductive cycles would mess with their results. As a consequence, the male body became "the norm," and the female body was never properly studied.
No surprise, then, that women's health is still full of mysteries.
Endometriosis, for example, a chronic condition in which tissue like the uterus lining grows where it shouldn't and that often causes severe period pain, affects more than 170 million women worldwide, yet it takes in the U.S. seven to 10 years on average to be diagnosed. Or take a totally different example: hip replacements. A 2013 study found that women with metal hip implants were 29% more likely than men to have them fail, possibly because of anatomical differences and too little testing in women.
We could go on for hours.
The conclusion is that, despite improvements, there remains a gap in women’s health studies.
“Women have been treated like an afterthought for far too long.”
But there's light at the end of the tunnel. In 2024, funding for women's health startups grew by more than half, reaching nearly $1 billion. And the global femtech market is expected to more than double, from $39 billion in 2024 to $97 billion by 2030. Finally, there are over 200 startups focused on women's health that have launched since 2019.
Among all these names, Clair stands out because it doesn't treat women's hormones as a feature but as the architecture.
Clair offers a wristband that tracks women's hormones like estrogen and progesterone without blood tests, using biosensors and AI to read the body's signals across the cycle.
Instead of treating a woman's natural monthly changes as a detail like other wearables have done, Clair treats them as the "primary signal," per the company. In other words, the wristband was designed around women's bodies from day one, something that rarely happens with wearables.
“Our models understand that cyclical variation is the core biological reality -- that the body's shifting cardiovascular, thermoregulatory, autonomic, metabolic, and sleep patterns across the menstrual cycle are not deviations from a baseline but expressions of the underlying hormonal state. This is not a feature layered onto a fitness tracker. It is the foundational design principle.”
A regular wearable may collect the right data and still read it the wrong way, treating a woman's normal hormonal changes as "noise to be smoothed over."
“A woman's HRV dropping 12% in her luteal phase looks like a recovery problem to a fitness algorithm. Her resting heart rate rising 3.5 BPM after ovulation looks like declining fitness. Her sleep efficiency changing in the premenstrual window looks like a sleep hygiene issue. It is none of these things. It is normal hormonal physiology -- and a system that does not understand this will systematically misinterpret half the population's data.”
Clair considers its product a continuous hormone monitor and compares itself to continuous glucose monitors, the small sensors many people with diabetes wear to track their blood sugar all day long. Clair wants to do the same for hormones by reading signals from the body continuously and noninvasively.
On privacy, Clair says health data is processed on your phone and encrypted. It never sells or shares data, and it follows the same security standards as U.S. healthcare providers, even though wellness devices aren't legally required to.
Looking ahead, Clair plans to add perimenopause monitoring, help fine-tune hormone replacement therapy, and even support the diagnosis of conditions like polycystic ovary syndrome, a hormonal imbalance that can disrupt periods and fertility, and the painful endometriosis we mentioned earlier. The company wants to help women going through perimenopause and menopause by giving them data they can share with their doctors, a much better solution than describing their symptoms from memory.
Clair launches in November 2026 as a wellness product, a category that doesn't need FDA clearance. That's the goal for Clair 2.0, which will go through the FDA's 510(k) process. This, and the trust of doctors and specialists, will make Clair stand out.
So far, after one year, Clair reports 94% accuracy in identifying cycle phases. However, that was measured against daily urine tests, and no peer-reviewed clinical data has been published yet. The company is running an independent clinical trial at Stanford, and it was recently hiring for roles like Clinical Research Coordinator and Lab Scientist. Plus, behind the product is a team of clinicians, scientists, and engineers from consumer tech, medical devices, and academic research, with advisors from Stanford Medicine. All of that signals a company that wants to earn trust with proof.
With all that in mind, we believe Clair is on the right path to becoming a standout, mission-driven product in an underserved yet massive market.
How It Works: Your Questions, Answered [Clair Blog]
The Data Was Always There [Clair Blog]
WoW Woman in Wearable Tech - Jenny Duan, CEO and Co-Founder of Clair Health [Woman of Wearables]
