Decoding hormones without blood rests. That’s the promise. And it’s a big one.
When a Stanford-born startup called Clair stepped into the spotlight earlier this year, it tapped into something that’s long been missing in health tech: real, continuous visibility into women’s hormones.
No needles. No labs. Just a wrist-worn device claiming to map hormonal shifts in real time.
It sounds like the future.
But how much of it is science and how much is still a work in progress?
Let’s dive in to understand.
What Clair actually does (and claims to do)
Clair is a women’s health startup founded by Stanford graduates Jenny Duan and Abhinav Agarwal. It is building a wrist-worn wearable designed to track hormonal changes continuously, without relying on blood draws, urine tests, or lab visits.
But it doesn’t measure hormones directly.
Instead, the device uses a combination of biosensors to track physiological signals, such as:
- Skin temperature
- Heart rate variability (HRV)
- Respiratory rate
- Sleep patterns
- Electrodermal activity
These signals are then fed into its AI models that estimate levels of key reproductive hormones like estrogen, progesterone, luteinising hormone (LH), and follicle-stimulating hormone (FSH).
Based on this, Clair claims it can offer:
- Continuous hormone “intelligence” instead of one-time lab snapshots
- Around 94% accuracy in identifying cycle phases
- Early detection of ovulatory patterns, such as the LH surge
The wearable is expected to ship later this year, with clinical trials underway to further validate its performance.
Why this matters: Hormones are finally getting attention.
For decades, women’s health, especially hormonal health, has been underrepresented in both research and consumer health technology.
Most wearables today track steps, sleep, and heart rate.
But very few attempt to decode the hormonal layer that influences everything. From energy and mood to metabolism and reproductive health.
That’s why Clair has generated so much conversation.
In the LinkedIn discussion around the launch, there’s a clear sense that this kind of innovation is long overdue.
Dr Christy Lane (Investor, Co-Founder at Flora, Clinical Scientist) captured the sentiment well:
“Women’s health has been understudied and underfunded. We need devices like this… Women have been asking for this type of data forever.”
She also draws a parallel to early versions of the Apple Watch. Imperfect at first, but evolving with better validation and iteration.
The excitement, in other words, is not just about Clair but about what it represents.
The catch: It doesn’t actually measure hormones
This is where things get more nuanced.
Clair does not directly measure hormones in blood, saliva, or sweat. Instead, it infers hormonal patterns from secondary physiological signals.
And that distinction is critical.
As Ute Wenning pointed out, wearables like this:
“capture the body’s response to hormonal processes, not the hormones themselves.”
That makes them useful for tracking patterns over time, spotting trends and building awareness. But not for clinical diagnosis and precise hormone measurement
The scientific challenge: Correlation vs reality
One of the most detailed critiques came from Gilles Frydman, a pioneer of patient-led healthcare communities and long-time advocate for patient empowerment.
He highlighted the complexity of hormonal biology, especially its circadian nature.
Hormones like cortisol, LH, and progesterone fluctuate not just daily, but in specific time-dependent patterns. They vary across the menstrual cycle and are easily altered by stress, sleep and environment.
According to him, validating a wearable like Clair requires more than comparing it to a single blood test. It requires understanding how well it tracks these fluctuations across a full 24-hour cycle.
Which means:
- Indirect signals must reliably reflect hormonal changes.
- AI models must hold up across diverse users.
- Validation needs to be longitudinal, not one-off.
And that level of validation is still in progress.
Where Clair stands today
A promising idea, but not fully proven yet.
Clair sits at an interesting intersection between consumer wearable tech and clinical-grade diagnostics.
On one hand, it represents a meaningful shift:
- Moving from reactive testing to continuous monitoring
- Giving women more visibility into their bodies
- Expanding the scope of wearable health beyond fitness metrics
On the other hand, science is still catching up.
Even the company acknowledges that further clinical validation is underway, with independent trials expected to strengthen its claims.
Final thoughts
Clair reflects a larger shift in healthtech, where hormones are finally being recognised as a core layer of human health, not a niche concern.
The excitement is justified.
The need is real.
But so is the scepticism.
Until stronger clinical validation is available, tools like Clair should be seen as complementary—not definitive.
Because when it comes to something as complex as hormones, data alone isn’t enough. It’s the accuracy and interpretation of that data that truly matters.
-By Rohini Kundu and the AHT Team
