A New Category in Women’s Health Wearables
Clair Health’s hormone-tracking wearable is a noninvasive wristband designed to continuously monitor key female hormones through physiological signals, opening a new category of women’s health wearables that shifts hormone testing from occasional lab work to daily, real-world tracking of the menstrual cycle and related health states. Backed by USD 11.6 million (approx. RM54.0 million) in seed funding led by Khosla Ventures with participation from a16z’s speedrun accelerator and others, the startup positions its device as the first noninvasive hormone tracker aimed at continuous use. Founders Jenny Duan and Abhinav Agarwal built on experience with noninvasive glucose monitoring to create a system that reads estrogen, progesterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) without blood or urine. Clair plans a wellness-focused launch while pursuing regulatory clearance later, signaling a phased route from consumer use toward more clinical applications.
How Clair’s Continuous Hormone Monitoring Works
The wrist-worn hormone tracking wearable combines 10 biosensors, including biomagnetic sensors, to monitor skin temperature, heart rate variability, electrodermal activity, and other signals. Clair’s AI models interpret more than 130 proprietary biomarkers to infer where a user is in their hormonal cycle and to estimate levels of estrogen, progesterone, LH, and FSH. According to Clair, internal testing shows 94% accuracy in classifying menstrual cycle phases when compared with daily urine samples. An independent study through the Stanford Gladstone BeeHive program is underway, with peer-reviewed data still to come. The company has also trained AI to read voice-based biomarkers and estimate cycle phase after a few minutes of conversation, hinting at future interfaces that may not even require wearing the device at every moment. For now, the focus is on reliable continuous hormone monitoring from the wrist.
Revealing Hidden Complexity in Female Physiology
Traditional hormone testing depends on a blood draw or urine test taken at a single time point, yet hormones fluctuate hourly and daily. Continuous hormone monitoring could expose richer patterns that help explain symptoms around mood, sleep, performance, and pain. In beta testing, Clair reports identifying nine sub-phases of the menstrual cycle, more than double the four broad phases most people learn, suggesting that the cycle may contain finer-grained physiological states with distinct signatures. Co-founder Jenny Duan notes that common wearable metrics such as heart rate variability, sleep, and breathing are strongly shaped by hormones, which might explain why many women find existing trackers less predictive or consistent. By layering hormone data onto everyday signals, the noninvasive hormone tracker could help users better time fertility efforts, understand diagnoses like PCOS, refine training and recovery plans, and prepare for perimenopause transitions.
Design, Privacy, and Market Signal
Clair frames its device as jewelry-inspired, signaling an intention to make hormone tracking socially acceptable and comfortable to wear daily, rather than medical-looking. The first run of 5,000 units sold out six months ahead of the planned November release, and the company says its waitlist has passed 25,000 people, plus more than 100 letters of intent from fertility clinics. Rock Health has reported that 57% of adults own a wearable or connected device, so new entrants must offer a clear, differentiated use case; continuous hormone data is Clair’s bet. The company also emphasizes privacy, processing data on the user’s phone and protecting it through zero-knowledge encryption rather than defaulting to cloud storage. Together, the seed funding, early demand, and investor mix suggest rising confidence that personalized women’s health wearables—built around hormones, not only steps and sleep—are set to become a major product category.
