Clair: World's First Wearable Hormone Tracker

Continuous. Noninvasive. Real time. The phrase sounds like something from the future, yet it now sits on the landing page of a young company promising the world’s first wearable hormone tracker designed for women, by women. Clair is not another step counter or sleep band with a cycle feature tucked into the settings. It is a device built around a single question that has been overlooked for decades in consumer tech. What would it take to see a living map of female hormones as they rise and fall through everyday life.

Why hormones have been a blind spot

For years, hormone tracking has forced women into an awkward choice. Either go through invasive, expensive blood tests and lab visits, or use one off finger prick kits and urine strips that deliver snapshots instead of a moving picture. Those snapshots are helpful, but they freeze a system that never really stands still, especially for people with irregular cycles or conditions like PCOS.

Most familiar wearables focus on steps, calories, heart rate and generalized sleep stages. They sometimes add period predictions on top of that, but those predictions lean heavily on calendar math and assumed averages rather than actual hormone data. Around thirty percent of women have irregular cycles, which means any tool built around a tidy twenty eight day template will quietly fail a large group of users.

That blind spot matters because reproductive hormones help shape mood, energy, sleep quality, metabolic health and even how the brain responds to stress. Clinicians note that more continuous hormone information can improve diagnosis and treatment of a range of conditions, not just fertility challenges. Yet until recently there simply was no practical way to collect that kind of data outside a research study.

What Clair actually is

Clair is a wrist worn wearable that aims to turn hormone dynamics into everyday information, using a sensor stack and machine learning models instead of needles, urine cups or test strips. The device is being developed by Clair Health, a Stanford founded startup led by Jenny Duan and Abhinav Agarwal, with a mission to make hormone intelligence as accessible as heart rate data.

On the surface, Clair looks like a bracelet that pairs with a mobile app. Under that familiar form, it is designed explicitly as a hormone first device. Rather than treating cycle tracking as a side feature, the entire hardware and software stack is oriented around mapping estrogen, progesterone, luteinizing hormone and follicle stimulating hormone over time. The company also mentions progesterone metabolite PdG among the hormones it aims to infer continuously.

The first version is expected to launch as a general wellness product, offering cycle phase classification, trend views and events like ovulation confirmation, with numerical hormone values planned for a later, FDA cleared iteration. That staged approach tells consumers two things at once. Clair wants to be useful soon, but it also wants clinical credibility rather than stopping at the wellness label.

How Clair listens to the body

Clair is not directly measuring hormones in blood, saliva or sweat. Instead, it leans on a principle that endocrinologists know well. When hormones shift, they ripple through multiple systems in the body at once. Skin warms slightly, tissues retain more or less fluid, the balance between sympathetic and parasympathetic activity tilts, heart rate patterns change and sleep architecture reshapes itself.

To capture those ripples, Clair packs ten biosensors into the wrist band. Public descriptions list skin temperature, resting heart rate, heart rate variability, breathing rate, sleep architecture, electrodermal activity and motion among the streams it records. The device then derives more than one hundred thirty proprietary biomarkers from those raw signals, spanning cardiovascular, thermoregulatory, autonomic, electrodermal, body composition and sleep domains.

On the software side, Clair trains machine learning models to learn the mapping between these multi system signatures and underlying hormonal states, using clinical grade hormone assays as ground truth rather than self reported period dates. In other words, it watches what happens across those many channels in real time, and asks what combination tends to correspond to a given phase of the cycle or to an upcoming surge in LH. The company explicitly frames this as hormonal inference, drawing an analogy to continuous glucose monitors that infer blood glucose from interstitial fluid rather than sampling blood directly.

What the early data says

Any new health technology that leans heavily on modeling has to answer an obvious question. How well does this inference actually work. Clair has shared some initial validation metrics from studies on more than forty women, capturing data across one hundred twenty seven cycles and more than five thousand days of wear.

From that early dataset, the company reports an accuracy of around ninety four point one percent for classifying cycle phase based on wearable signals alone. It also reports about eighty seven percent sensitivity for detecting LH surges, with timing accuracy within roughly one point two days. Importantly, Clair emphasizes that its models were trained on diverse physiologies, including women with irregular cycles and PCOS, in an attempt to avoid overfitting to textbook patterns.

These numbers are promising, but they are still early stage. The company plans a larger clinical study program, including a trial at Stanford Medicine, to better establish how well the system performs across different ages, conditions and life stages. For now, users should see the claims as encouraging signs rather than final clinical proof.

Day to day experiences Clair wants to unlock

Where Clair becomes interesting is not only in the technology, but in how it could reshape daily decisions if it works as intended. Hormones touch almost every aspect of lived experience, yet most people only see them in lab reports or fertility app predictions. Clair’s founders and early coverage highlight several practical use cases.

For women trying to conceive, continuous monitoring could refine fertile window detection and confirm ovulation without disposable strips or repeated blood draws, which can be costly and emotionally draining. Instead of relying on calendar averages, users would see how their own hormones behave in real time, including in irregular or anovulatory cycles.

Athletes and highly active women are another focus. Hormonal fluctuations influence training capacity, recovery, injury risk and perceived exertion. Clair aims to let users align intense sessions, deload periods and recovery strategies with their hormonal landscape, rather than forcing a uniform plan across all phases of the cycle. This fits a growing push in sports science to take female physiology seriously instead of treating women as smaller versions of male athletes.

Perimenopause and later life stages form a third important area. The transition toward menopause is marked by unpredictable shifts in cycle length, sleep quality, vasomotor symptoms and mood, all driven by changing hormone patterns. Continuous hormone linked data could help make sense of those changes, giving women more tangible information to bring to clinicians and to guide lifestyle adjustments.

Even outside specific diagnoses or life stages, Clair positions itself as a tool for understanding how hormones influence everyday variables like mood, productivity and sleep, inviting users to spot patterns over months instead of guessing day by day.

Designed for women in more than name

Clair leans heavily on the idea that it is built for women, by women. The company explicitly describes the device as the first continuous noninvasive hormone monitor designed around female biology and its changing needs across life stages. The founding story reinforces that message. Jenny Duan’s interest in women’s health and technology grew out of her undergraduate experience, including projects focused on endometriosis and coursework that pushed her toward building solutions in the women’s healthcare space.

The team frames Clair not just as a consumer gadget but as part of a broader attempt to close gaps created by the historic underrepresentation of women in medical research and clinical trials. By generating continuous, real world data from diverse users, they hope to support more precise understanding of how hormones affect health, mood and function beyond the narrow lens of reproduction.

That mission first framing is part of what makes Clair compelling to many observers in the femtech and digital health communities. It exists at the intersection of personal empowerment, clinical research and long standing frustration with one size fits all health tools that quietly assume a male default.

Privacy, data and trust

Whenever a device touches intimate health data, trust and privacy move to the foreground. Clair has repeatedly described its product as privacy first. One notable design choice is that data processing is planned to happen locally on the user’s phone rather than in remote data centers, in contrast to many mainstream wearables. That architecture aims to reduce exposure of sensitive hormonal and reproductive health information to third parties, a concern that has grown sharper in the current political climate.

The device connects to a mobile app that serves as the interface for insights, trends and event notifications. By keeping computation and storage close to the user, Clair positions itself as a more cautious steward of data, though real world trust will still depend on how transparent the company is about data policies, partnerships and any future cloud features. Potential users will need to read privacy terms carefully and watch for external audits or third party assessments as the product matures.

Pros that make Clair stand out

Clair’s biggest strength is that it attacks a problem worth solving. Hormonal health has long been underserved in both medicine and consumer technology, and a device that centers hormones rather than treating them as a side metric fills a genuine gap. The focus on passive, continuous tracking lowers friction dramatically compared with repeated lab visits or home tests that require active effort every time.

Technically, Clair’s use of multi modal sensing and clinically anchored models is a step beyond simple calendar based apps or single metric devices that rely on temperature alone. By measuring ten biosignals and more than one hundred thirty biomarkers, then training on real hormone assays, the system is better positioned to separate hormonal patterns from everyday confounders like caffeine, illness or a bad night of sleep. Early accuracy numbers for cycle phase classification and LH surge detection, while still limited, suggest the approach has real promise.

The planned span of use cases is also a plus. Clair is not just for one narrow window such as fertility. It is being built to stay relevant from first period through menopause, with applications in training, mental health awareness, cycle literacy and long term hormonal health monitoring. If the company follows through on its clinical study program and regulatory path, users may eventually have a tool that bridges wellness and medicine rather than living only on one side.

Limitations and open questions

At the same time, there are real limitations and risks that deserve attention, especially for readers who prefer a balanced view over pure enthusiasm. Clair’s validation work so far, while encouraging, involves a relatively small cohort. More than forty women and one hundred twenty seven cycles is a start, not a definitive answer across all ages, ethnicities, body types and health conditions. Larger, independent studies will be needed to verify accuracy and usefulness in the wild.

The current product will launch as a wellness device without full FDA clearance, which means that for now it should be treated as an informational tool, not a stand alone diagnostic or treatment guide. Even as models improve, there is always a risk of false positives or missed events, particularly for users with complex endocrine conditions. People will still need clinicians to interpret patterns and integrate them into care plans.

There are also practical questions around accessibility and cost. Clair’s official site invites users to join a waitlist and mentions a significant launch discount, which implies that the eventual price will likely place it in the premium wearable category. That level may be out of reach for many people who could benefit from better hormone insights, at least in the early years. Finally, although the company emphasizes on device processing and privacy, only time and transparency will show how fully that commitment holds up under commercial pressures.

Where Clair fits in the future of women’s health

Clair is entering a landscape where interest in hormone health has exploded. Social platforms are full of content about balancing hormones, syncing life to the cycle and decoding unexplained fatigue or mood swings. At the same time, a race is underway among startups to deliver something close to continuous hormone monitoring, whether through advanced lab kits, urine based systems or other sensor approaches.

In that race, Clair’s choice to build a hormone specific wearable from the ground up feels significant. It signals that hormones are important enough to deserve their own hardware and modeling stack, rather than being an add on tucked behind a step counter. If the technology performs as early numbers suggest, it could shift expectations for what women demand from their health tools, from vague predictions to detailed, personalized hormone intelligence.

That shift will not happen overnight. It will require careful science, honest communication about limits and a willingness to prove clinical value beyond the hype of being first. But even at this early stage, Clair embodies a quiet but powerful idea. Hormonal health should not be a black box that women peer into a few times a year. It should be visible, continuous and understandable, worn on the wrist like any other part of a daily routine.

References

Clair Health. (n.d.). Clair. Continuous hormone monitor. Retrieved February 2026, from https://wearclair.com

FutureFem Health. (2026, February 10). Clair emerges from stealth with plans to launch continuous hormone tracking wearable. Retrieved February 2026, from https://www.futurefemhealth.com/p/clair-emerges-from-stealth-with-plans

LSN Global. (2026, February 16). Clair introduces continuous monitoring wearable for hormone health. Retrieved February 2026, from https://www.lsnglobal.com/article/view/32907

Stanford Daily. (2026, February 4). Stanford founded startup develops wearable for continuous hormone monitoring. Retrieved February 2026, from https://stanforddaily.com/2026/02/05/stanford-founded-startup-develops-wearable-for-continuous-hormone-monitoring

Juicy Byte. (2026, February 10). Meet Clair. The first continuous hormone monitoring wearable. Retrieved February 2026, from https://juicybyte.substack.com/p/016-the-juicy-chat-meet-clair-the

Reach Capital. (2026, February 5). Hormone intelligence made visible. Why we invested in Clair. Retrieved February 2026, from https://www.reachcapital.com/resources/news/hormone-intelligence-made-visible-why-we-invested-in-clair-health

Wellworthy. (2026, February 3). Clair just launched with the first continuous hormone tracker for women. Retrieved February 2026, from https://wellworthy.com/clair-just-launched-with-the-first-continuous-hormone-tracker-for-women

Fitt Insider. (2026, February 12). Clair debuts continuous hormone wearable for women’s health. Retrieved February 2026, from https://insider.fitt.co/clair-unveils-continuous-hormone-wearable