A Wearable Built For What Smartwatches Skip
Clair Health, a San Francisco startup, is building a jewelry-style wristband that reads ten signals from the body and uses machine learning to estimate where a woman is in her hormonal cycle, without a blood draw, a finger prick, or a urine strip [1] [2].
On June 17, 2026, the company said it had raised $11.6 million in seed funding led by Khosla Ventures, with participation from a16z speedrun, Reach Capital, Brydge Club, Cartan Capital, and angel investors including 23andMe founder Anne Wojcicki [2] [3]. TechCrunch reported the round as $11 million; the company and several outlets put the exact figure at $11.6 million [1] [3].
How a Wristband Tries to Read Hormones Without Drawing Blood
Clair does not measure hormones. It infers them.
Measuring a hormone like estradiol directly is hard, because the molecule is large and lacks the optical properties most wearable sensors rely on [5]. So instead of reading the hormone, Clair reads what the hormone does to the rest of the body. As estrogen and progesterone shift across a cycle, so do skin temperature, heart rate variability, electrodermal activity, fluid retention, and the balance between the sympathetic and parasympathetic nervous systems [5]. Clair's wristband carries a stack of ten biosensors, including a biomagnetic sensor the company says is not found in any competing consumer wearable, and runs more than 130 proprietary biomarkers through machine-learning models to estimate activity across four hormones: estrogen, progesterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) [2] [3] [6].
The company reports two headline results from its beta. First, its model identified which phase of the menstrual cycle a woman was in 94% of the time, benchmarked against daily urine samples, the same standard used by at-home ovulation strips rather than a clinical blood analysis [2]. Second, and more provocatively, Clair says continuous monitoring revealed nine distinct sub-phases of the hormonal cycle, where women are traditionally taught there are four [3] [7]. Co-founder Abhinav Agarwal told Longevity.Technology that continuous modeling of the hypothalamic-pituitary-ovarian axis, the feedback loop between the brain and the ovaries, suggests the ovary moves through nine physiological stages, some of which appear in scientific literature but have been hard to observe because hormone testing has always been episodic [7].
If that sounds familiar, it should. A continuous glucose monitor measures glucose in interstitial fluid, while Clair is trying something harder: inferring hormone patterns from proxy signals.
Who Built Clair
Clair was co-founded by two recent Stanford graduates, Jenny Duan and Abhinav Agarwal, who met at Stanford in spring 2025 and began building the company soon after [2] [4]. It came out of stealth in February 2026 [5].
Duan, the chief executive, studied symbolic systems at Stanford and closed the seed round around the time she graduated in 2026 [2]. Her interest in women's health predates the company. In high school she worked with women experiencing domestic violence and homelessness through a nonprofit in Oregon, where she repeatedly watched providers dismiss women's symptoms for lack of quantitative data [6]. At Stanford she built apps focused on endometriosis at a campus hackathon, and a junior-year course on philanthropy for sustainable development pushed her toward building something in the space [4]. Before Clair she co-founded a creator community that reached more than 10 million people and worked on the marketing team for a consumer shopping product [5]. Agarwal, the chief technology officer, earned his bachelor's and master's degrees at Stanford and previously helped build what its investors describe as the world's first noninvasive continuous glucose monitor, bringing the biomedical-signal and wearable-hardware background the inference approach depends on [4] [5].
The cap table leans into women's health. Khosla Ventures partner Alex Morgan, who led the round, framed the thesis bluntly, saying that much of wearable technology has been "bro-tech for tech-bros" and that Clair's team identified a large, underaddressed market of women wanting insights designed for their physiology [2]. The company holds provisional patents on its sensor configuration [2]. It plans to launch the wristband in late 2026 at $369 for the device plus a $9.99 monthly subscription, has gathered a waitlist of more than 25,000 people, sold out its presale, and says it has received more than 100 letters of intent from fertility clinics [1] [2].
Inference Is Not a Diagnosis
Clair is launching as a wellness product in late 2026 and pursuing US Food and Drug Administration (FDA) clearance later, because the wellness path is faster to market [2]. To its credit, the company says it is running an independent clinical trial through a Stanford program, with plans to publish peer-reviewed results [4] [6].
That trial, more than the funding, is the thing to watch. A wrong signal has low stakes when it is a missed workout suggestion and high stakes when it is ovulation timing or a perimenopause transition. Roughly 30% of women have irregular cycles, the exact group for whom calendar-based predictions already fail and for whom an inference that is confidently wrong could be worse than no number at all [6]. Clair is not alone in chasing this market, and some rivals measure more directly: Eli Health uses at-home saliva testing, and Inne has secured European regulatory clearance for a saliva-based hormone monitor used for contraception [6]. Clair's wager is that a device you already wear every day beats a cartridge you have to remember to use, as long as the guess is good enough. Whether it is good enough is still being tested.
None of this is a reason to dismiss the device. It is a reason to be precise about what it is: a sophisticated, continuous estimate, not a lab result, and not a doctor.
Why This Matters for Concierge and Direct Primary Care
Step back and the Clair story is really about a problem that hormone data makes obvious: a number is only as useful as the person who interprets it and acts on it. This is the same gap that showed up when Oura's smart ring added a path to a doctor and when WHOOP's $575M raise pushed it toward clinical features. The wearable layer keeps reaching up toward care, but a wristband cannot examine you, order a confirmatory test, adjust a prescription, or decide whether your pattern needs watching or a referral this month.
The bottleneck is time, and time is a function of panel size. A traditional primary care doctor often carries a panel of 2,000 to 2,500 patients, which is the underlying reason you wait weeks for an appointment and get 10 to 15 minutes when you arrive. A concierge physician carries a panel of under 300, and a direct primary care (DPC) doctor up to 800, with visits that run 30 to 60 minutes [8]. That is the difference between a doctor who glances at a number and a doctor who has time to scroll six or twelve months of your hormone, sleep, and recovery trends and connect a pattern to the symptom you mentioned. The Society of Actuaries' 2020 evaluation of DPC found patients visited the emergency room 40.51% less often than insurance-only patients, and the mechanism behind that figure is access plus relationship, not a better dashboard [8].
Hormone health is one of the strongest examples. Conditions like polycystic ovary syndrome (PCOS) and endometriosis are not rare, just slow to diagnose, and perimenopause is a years-long transition many women navigate with little guidance. These are areas where concierge and functional-medicine practices already spend real time. Practices built around prevention, like Age Better Miami, fold patient-generated data into longevity and hormone-focused programs, and tech-forward practices like Sigma Humans in Chicago treat continuous biometric data as a normal part of the workup. A device like Clair gives that kind of doctor a richer input. It does not replace the visit. This is the same shift toward personalized, data-driven primary care that has been building for several years.
What Patients Should Do With a Device Like This
For a healthy woman who wants better insight into her own cycle, a hormone wearable is a reasonable thing to try when it ships, with two rules. First, treat the readings as a continuous estimate, not a diagnosis, until independent validation lands. Second, do not make a major decision about fertility, medication, or a worrying symptom on the strength of a wrist signal alone. Bring the data to a doctor who has time to read it.
That last part is where the device and the relationship stop being substitutes. Concierge medicine runs $3,000 to over $40,000 per year, and DPC runs $50 to $200 per month, or $600 to $2,400 per year [8]. A hormone wearable runs a few hundred dollars plus a small monthly fee [1]. One is a stream of data. The other is a physician who takes responsibility for what the data means. If you have both, the wearable becomes something an actual doctor reads and acts on, instead of one more app you check and forget. If you are weighing a more involved relationship, browse physician-led concierge and DPC practices in San Francisco or in your own city on NextMD.
FAQ
What is Clair Health?
Clair Health is a San Francisco startup, co-founded by Stanford graduates Jenny Duan and Abhinav Agarwal, building a noninvasive, continuous hormone-monitoring wristband for women [2] [4]. In June 2026 it raised $11.6 million in seed funding led by Khosla Ventures, and it plans to launch the device in late 2026 [1] [3].
How does Clair track hormones without a blood test?
It does not measure hormones directly. The wristband uses ten biosensors and more than 130 proprietary biomarkers to read physiological signals such as skin temperature, heart rate variability, and electrodermal activity, then runs them through machine-learning models to estimate activity across estrogen, progesterone, LH, and FSH [3] [6]. It is an inference from the body's response to hormones, similar in spirit to how a continuous glucose monitor estimates blood sugar [6].
How much will the Clair wearable cost?
Clair has said the device will cost $369, plus a $9.99 monthly subscription, at its planned late 2026 launch [1]. The company reported a waitlist of more than 25,000 people and a sold-out presale [2].
Is Clair FDA approved?
Not yet. Clair plans to launch as a wellness product first, which is the faster path to market, and to pursue FDA clearance later [2]. The company says it is running an independent clinical trial through a Stanford program and plans to publish peer-reviewed results, which is the validation to watch before relying on its readings for medical decisions [4] [6].
Can a hormone wearable replace seeing a doctor?
No. A wearable can surface a trend, but it cannot examine you, order a confirmatory test, manage a condition like PCOS or perimenopause, or coordinate your care. Those require a physician relationship, and the time to do it well is why concierge and DPC doctors carry far smaller patient panels than traditional primary care [8].
Find a Concierge Doctor
A wearable tells you what might be happening in your body. A doctor who knows you tells you what to do about it. Use NextMD to find concierge and direct primary care practices in your city and compare prices.
Search concierge doctors near you on NextMD →
Sources
Ivan Mehta (2026) Two Stanford grads raise $11M to build a noninvasive wearable for hormone tracking. TechCrunch. Read on TechCrunch
Lazarus, L. M. (2026). Exclusive: A 21-year-old Stanford grad just raised $11 million to put a hormone lab on your wrist. Fortune. Read on Fortune
Femtech Insider. (2026). Clair Health Raises $11.6M to Build Noninvasive Continuous Hormone Monitor for Women. Femtech Insider. Read on Femtech Insider
Barnes, B. (2026). Stanford-founded startup develops wearable for continuous hormone monitoring. The Stanford Daily. Read on The Stanford Daily
Herrera, J. (2026). Making Hormone Intelligence Visible: Why We Invested in Clair. Reach Capital. Read on Reach Capital
Stengel, G. (2026). A 22-Year-Old Just Raised $11.6 Million To Read Women's Hidden Hormone Signals. Forbes. Read on Forbes
Garth, E. (2026). Clair raises $11.6m for continuous hormone tracking. Longevity.Technology. Read on Longevity.Technology
Busch, F., Grzeskowiak, D., & Huth, E. (2020). Direct Primary Care: Evaluating a New Model of Delivery and Financing. Society of Actuaries / Milliman. Read the SOA report (PDF)