Why Small UX Details Can Matter More Than Years of R&D
Interview with Eli Health CEO Marina Pavlovic Rivas
Guest
CEO of Eli Health
Marina is the co-founder and CEO of Eli Health, a company developing real-time hormone monitoring technology for continuous health tracking. A data scientist by training, Marina previously founded Gradiant AI, a machine learning company that was acquired in 2019.
Interview Summary
Marina Pavlovic Rivas is the co-founder and CEO of Eli Health, a company focused on making hormone data accessible in real time. Trained in data science, Marina started Eli after confronting a gap in healthcare: hormones fluctuate daily and influence nearly every system in the body for both men and women, yet they are typically measured infrequently — or not at all. While often siloed within fertility or women’s health, hormone data remains largely absent from everyday health tracking.
Eli Health aims to address that gap with a saliva-based testing system that delivers real-time hormone results through a mobile app. Designed for frequent use and seamless integration into daily routines, the product is guided by two benchmarks centered on ease of use and affordability. Those constraints shaped the company’s approach to design, regulation, and commercialization from day one.
Early in the process, Marina was told that building the required lab infrastructure would cost $3 million — more than she’d raised — and that achieving the necessary sensitivity levels wasn’t feasible. Rather than outsource, she chose to build everything in-house.
Today, Eli Health has launched commercially in the U.S. and Canada, starting with cortisol testing to measure stress, with progesterone and testosterone tests coming next. The company closed a $12 million Series A in June 2025.
Key Questions
How do you evaluate early design options without locking yourself into a form factor too soon?
What does beta testing reveal that years of lab or preclinical work can't?
How early should regulatory considerations shape product design decisions?
How do existing consumer spending patterns influence pricing and positioning decisions?
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Top Takeaways
Biology Sets the Boundaries. Adoption Decides the Form.
Marina knew Eli Health would measure hormones, but she didn't begin with a fixed format or sample type. That flexibility enabled the team to evaluate a wide range of options, including patches, watch add-ons, toilet analyzers, saliva tests, and blood draws. Two benchmarks guided the process: the product needed to be “as easy as brushing your teeth and as affordable as a cup of coffee.”
The evaluation framework had four layers:
Biological feasibility: Blood was the gold standard, saliva had strong validation, while interstitial fluid and sweat were unproven for hormones at scale.
Technical risk: Could a single platform work for multiple biomarkers?
Regulatory pathway: a patch with a needle likely meant Class II or de novo, while saliva could stay within wellness guidelines or Class I.
Manufacturing cost: Whether pricing would support broad adoption or limit use to clinical settings.
Saliva ultimately offered the most balanced path across all four criteria, shaping Eli’s regulatory strategy, pricing, and timeline to market.
➜ Constraints clarify the form factor.
Biological feasibility, technical complexity, regulatory pathway, and cost must be evaluated together, not sequentially. Clear benchmarks for ease of use and affordability help narrow the field early. In practice, the winning design is rarely the most technically ambitious — it's the one that fits naturally into a user’s routine and supports the behavior the product requires for adoption.
Using Private Beta Testing to Uncover UX Challenges That Could Prevent Adoption
Eli Health spent six years solving scientific and engineering challenges across chemistry, microfluidics, hardware, software, and AI. But technical rigor alone didn't ensure adoption. In private beta, the team noticed a failure point: users weren't pulling the test strip far enough — just a few millimeters short — preventing saliva from flowing. Years of validated technology were effectively sidelined by a detail that would take just a few hours to address.
The fix came through a series of small, deliberate changes. Marina's team added a visual dot that appeared once the strip was fully extended. They changed app instructions from "pull enough" to "pull until you see the dot." Even the interface changed, replacing the "Next" button with "I see the dot." Each adjustment was minor on its own, but together they helped unlock significant value.
Marina didn't wait for quarterly feedback cycles. She tested prototypes live at events, handing devices to people with zero context and watching where they hesitated. She points to ”The Mom Test” as a guide for gathering unbiased feedback.
➜ Adoption often hinges on the smallest interactions.
Years of R&D can be undermined by minor UX friction that prevents correct use. Use private beta testing to surface issues early — especially when products are placed in the hands of users without context. Continuous real-world testing often reveals the gap between technical validation and adoption, in hours of refinement, not years of development.
Anchoring to How Users Already Spend
Marina wanted impact at scale, which meant building a product people could use frequently, affordably, and without heavy regulatory friction. Wellness positioning aligned with those constraints, offering a lighter regulatory pathway, faster time to market, and pricing that fit with existing consumer behavior. Cortisol fit within wellness guidelines, while progesterone required Class I clearance for ovulation detection.
Consumer behavior supported the approach. Many smartwatch users already pay $300-500 annually for biomarker tracking, and CGM companies have begun expanding beyond reimbursement into direct-to-consumer models. Eli’s pricing followed a similar pattern: $99 for 12 tests, or roughly $300 per year — comparable to Oura subscriptions.
The main trade-off is education. Creating continuous hormone monitoring as a category requires educating users on why frequent data matters. “There’s a lot of work on the education side,” Marina notes. Still, anchoring pricing to familiar spending patterns reduced adoption friction while allowing different biomarkers to follow different paths as evidence and use cases evolve.
➜ Wellness positioning can lower the barrier to adoption.
New products gain traction faster when pricing and positioning align with how users already spend on health tools like wearables and wellness subscriptions. A wellness-first approach can reduce regulatory burden and accelerate market entry, while preserving the flexibility to layer in clinical claims as evidence and use cases evolve.
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