Making Hormone Intelligence Visible: Why We Invested in Clair

Last year, I started taking my fertility more seriously and I went to see a reproductive endocrinologist. Before long, I found myself on Amazon buying basal thermometers and ovulation sticks, while also making frequent trips back to the clinic for blood draws—just to understand what my hormones and reproductive cycle were doing. The process felt so analog and opaque. 

For all the progress we’ve made in consumer health technology, one of the most important biological systems in women’s health is still largely invisible. We can track sleep, recovery, steps, heart rate, and metabolic data. But when it comes to hormones, which influence fertility, menstrual regularity, mood, energy, stress response, and long-term disease risk, most women are still left with snapshots, proxies, and guesswork.

The problem isn’t that the data doesn’t exist. It’s that we haven’t had the right tools to capture and interpret it, continuously, non-invasively, and in real time.

Until now. We’re excited to share that we invested in Clair Health, a company building the first continuous, non-invasive hormone-monitoring wearable. Clair is aiming to make hormone intelligence as accessible and actionable as heart-rate data is today.

Hormones are foundational, but measurement is broken

Today, understanding our hormones typically involves one of two imperfect options. One option is infrequent testing, like blood draws or lab work, that’s expensive, inconvenient, and episodic. The other option is a growing number of consumer tracking tools that infer cycle and fertile windows from indirect signals like temperature and timing, but they aren’t very precise.

This leaves a massive gap. Women are making critical health decisions about fertility, Polycystic Ovary Syndrome (PCOS), irregular cycles, perimenopause symptoms, training, and recovery without reliable, real-time information about what their bodies are actually doing.

Clair’s insight: the signals were always there

Clair is building the first wearable designed specifically for continuous hormone intelligence. Not cycle tracking. Not fertility prediction as a side feature. But a hormone-first device that can help women understand what’s happening in their bodies without relying on blood draws, urine strips, or temperature-only proxies.

What makes Clair different is that they’re not trying to force hormone tracking onto an existing wearable form factor. They’re building the device from the ground up around a single question: What would it take to infer hormones non-invasively and continuously?

That leads to a fundamentally different approach, combining a purpose-built sensor stack with machine learning designed for multimodal fusion.

At the heart of Clair’s technology is a simple but powerful idea: the data was always there.

Directly easuring hormones like estradiol is incredibly hard. These molecules are large and lack the optical properties that many traditional wearable approaches rely on. But hormones don’t just exist in isolation—they drive downstream physiological changes throughout the body.

As estrogen and progesterone change, so do patterns like:

• fluid retention and tissue conductivity
• sympathetic versus parasympathetic balance
• vascular tone and heart rate variability
• temperature curves and autonomic response
  

Clair is designed to capture these signals and fuse them into hormone inference via the world’s first female biology world model. Clair turns the body’s natural physiological response into actionable, personalized hormone insights.

A team built for this category

This is a complex problem, and one that Jenny Duan and Abhinav Agarwal are poised to tackle. 

Jenny is deeply consumer-obsessed. Before Clair, she co-founded the NEXT Creator Collective, a community of creators that reached over 10 million people, and worked on Daydream’s marketing team during the launch of their consumer shopping product. When Jenny faced her own hormonal challenges, she became determined to build something that would help women take control of their health. Abhinav previously helped build the world’s first non-invasive continuous glucose monitor and brings deep expertise across biomedical signal processing, AI, and wearable hardware.

Together, they bring the rare combination this category demands: technical depth, consumer empathy, and the ability to turn complex science into something people can actually use.

Looking ahead

Clair is building toward a future where hormone intelligence is continuous, non-invasive, and personalized—unlocking proactive care for fertility, cycle irregularity, PCOS, perimenopause, athlete performance, and beyond.

Today, we’re excited to share that Clair is coming out of stealth. If you want to take control of your hormonal health, you can sign up to join the waitlist here.