Exclusive: A 21-year-old Stanford grad just raised $11 million to put a hormone lab on your wrist

Jenny Duan closed her seed round the same week she picked up her diploma. Duan, 21, graduated from Stanford University last weekend with a BS in Symbolic systems. She also closed an $11 million seed round for Clair Health, Fortune learned exclusively. Khosla Ventures led the round, with support from a16z Speedrun, Brydge Club, Treehub, Cartan Capital, AGI House, Insiders VC, and Anne Wojcicki. The startup, co-founded with Abhinav Agarwal, is building what it calls the first continuous, non-invasive hormone monitor for women. Instead of drawing blood or piercing skin, Clair Health’s wearable wristband uses a stack of 10 biosensors—including biomagnetic sensors it says are not found in any competing consumer wearable—to read physiological signals like skin temperature, heart rate variability, and electrodermal activity, then runs those markers through AI models to infer where a woman is in her hormonal cycle. “Right now, to measure hormones, you either do a blood test in a lab or you pee on a stick at home,” Duan told Fortune. “Any urine test is also not looking at hormones directly—they’re looking at how your body metabolizes them.” Clair’s AI 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, not a clinical blood analysis. Independent third-party studies, including one through Stanford, are underway and will eventually put harder numbers on the table. Other wearable tech companies have been circling this space. Whoop launched women’s hormonal insights in 2025 and expanded it with a women’s-specific blood testing panel this Spring. Smart ring maker Oura launched a proprietary AI model for women’s health in February 2026. And Natural Cycles already powers FDA-cleared birth control through Oura’s temperature sensor. None of it was built from the ground up for hormones though. “Much