WoW Woman in Women's Health I Justyna Strzeszynska, founder and CEO of Joii
Justyna Strzeszynska is the founder and CEO of Joii, a women’s health startup transforming menstrual health and period tracking.
With a background in product development and financial management, she launched Joii to address the lack of accurate menstrual blood measurement after her own experience navigating menstrual health challenges. Like millions of women globally, Justyna had menstrual health concerns and recognised the severe lack of technological advancements in the women’s health and period care industry. Motivated by her personal journey, Justyna established Joii with a vision to create a solution that transforms menstrual health management. Since 2018, she’s led Joii through clinical research, product development and UK medical device registration, with a mission to make menstrual measurement standard in healthcare.
Joii is a UK-based women’s health startup that has developed the world’s first AI-powered app and pad system to accurately measure menstrual blood loss. Registered as a Class I medical device, Joii enables users to track their period volume and symptoms, supporting faster and more accurate diagnosis of conditions like endometriosis and fibroids. Joii’s mission is to bring clinical data and better care to an area of health that’s long been overlooked. Its range of period care products focuses on high performance and sustainability to ensure they tread as lightly on the planet as possible. Founded in 2021, the business has received an EIT Digital Innovation Factory Grant as well as a place on the DigitalHealth.London launchpad programme.
Tell us a bit about your background.
My background is in investment product development. I worked in the finance industry for several years, developing investment products and supporting go-to-market strategies. After leaving corporate, I ran a small angel investment network that supported early-stage founders.
The journey to Joii started through my own personal experience. I struggled with heavy periods and the uncertainty and dismissal that often surrounds menstrual health. I kept thinking 'how is it possible that we can measure steps, sleep, oxygen saturation and even stress, but we cannot measure menstrual blood loss?' That question stayed with me. I began researching the clinical science behind menstrual blood quantification in 2018 and that research evolved into the foundation of Joii.
How did you get into this industry? Has it been easy, or were there many challenges?
I didn’t begin in healthtech. I arrived in the industry because I saw a problem that was being ignored.
When I started talking about measuring period blood loss using a phone, I was met with a lot of raised eyebrows. Menstrual health has been historically under-researched, under-funded and socially uncomfortable to talk about. So there were challenges, including convincing others that menstrual health is not niche, it is fundamental health data. Other challenges were securing funding in a landscape where women’s pain is often minimised and translating clinical measurement techniques into something accessible and everyday.
I have found that once women hear what Joii does, the response is immediately “I wish I had this years ago.” That validation has kept the momentum going.
How long did it take to be where you are now, and what was the biggest obstacle?
It has been a multi-year journey from initial research in 2018, through to early prototypes, dataset development, clinical partnerships, obtaining Class I Medical Device status and now the launch.
The biggest obstacle has not been technology, it has been changing expectations. We’ve been taught to normalise pain, guesswork and uncertainty when it comes to periods, but Joii is fundamentally changing that narrative and cultural change takes time.
What are your biggest achievements to date? (Include the UK launch here.)
Our biggest achievements to date include obtaining Class I Medical Device status for the Joii app and officially launching in the UK.
I am also proud of completing clinical usability and patient experience studies, which showed Joii improves communication with clinicians and menstrual health understanding, and launching the Joii Day and Night Evaluation Pads in Ireland, making them available in pharmacies and health stores.
The achievement I’m most proud of is the community, and women who say 'for the first time in my life, I feel like my period makes sense.”
What projects are you currently working on?
We are currently working on further clinical validation studies exploring how menstrual blood loss patterns correlate with conditions like endometriosis, adenomyosis, fibroids and PCOS. We're also working on an AI model expansion to support pattern recognition and early symptom pathway guidance, as well as partnerships with healthcare providers and research institutions to integrate menstruation into routine diagnostics. We're also building community-led menstrual health education, especially for teens and young adults. Our long-term mission is to make menstrual measurement standard in healthcare.
Is the #WomenInTech movement important to you and if yes, why?
The #WomenInTech movement is important to me, especially now with the rise of AI. If women are not involved in developing and steering these technologies, we risk building systems that repeat the same biases we already see in healthcare.
It’s not about having women “represented”, it’s about making sure the assumptions and datasets behind these tools actually reflect women’s real experiences. I think women need to be part of the research, the design and the decision-making around AI, otherwise we’ll miss the opportunity to make these tools genuinely useful and fair.
What key trends do you see in your industry in the next five years?
AI will play a big role in earlier detection and clinical support in women’s health. We’re already seeing AI help with earlier breast cancer detection and ovarian cancer risk assessment. There’s real potential.
But the important part is how it’s built. A lot of medical datasets underrepresent women, and especially diverse women. If that isn't addressed, AI will simply repeat existing gaps in diagnosis.
So I think the trend will be AI being used to support earlier identification of conditions like endometriosis, adenomyosis and heavy menstrual bleeding, plus a growing focus on making sure the underlying data is representative and clinically sound.
Women need to be involved in that, not just as users, but as contributors to the research and the technology itself.
What advice would you give to someone starting a career in this industry?
It depends on your background, but the main thing is to understand the problem properly. Women’s health is full of products that sound good, but in reality, don’t solve anything. Before building a product or service, it's vital to spend time with women and clinicians and conduct thorough research. Look at what’s already been tried and why it hasn’t scaled.
Also, be prepared for it to take longer than you think. Regulation, evidence and clinical validation are slow processes.
Finally, find people who actually care about the mission. This space requires patience and consistency. If you have that, and you stay close to the real problem, you’ll find your direction.
Who are three inspirational women in your industry you admire?
There are a lot, but a few stand out to me based on what they’ve actually built:
Ida Tin, who coined the term Femtech and made it possible for companies like ours to be recognised as part of a real sector, not a niche.
Valentina Milanova, founder of Daye, for bringing product innovation into menstrual care and proving that this market deserves R&D, not just rebranding.
Dr Regina Barzilay (MIT), whose work in AI for early breast cancer detection shows how thoughtfully designed AI can meaningfully improve outcomes in women’s health.
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