From coding to contraception: the physics behind fertility


Natural Cycles is a natural method of contraception that’s delivered in the form of an app, used in conjunction with a basal thermometer. It can be used for contraception, conception, or tracking fertility. Kathryn Reilly talks to co-founder, Elina Berglund, about the female entrepreneur’s perspective

It had been my dream since the age of five to become a physicist. I had a fascination with the stars and the universe, which was nurtured by my parents. Before I could read, they would borrow books from the library and read to me about black holes and galaxies at bedtime. As my interest and understanding grew, I began to realise that to understand the ‘big stuff,’ I would first have to understand the smallest, most fundamental building blocks which inform the way our world works, and this led me to study particle physics at university. After finishing my PhD at CERN (The European Organization for Nuclear Research), I continued to pursue my research there as part of the Higgs Boson discovery team. It was such an exciting time – our team worked day and night for many months to make that discovery; being part of that team and part of that research was my greatest achievement at CERN.

One of few

The field of physics is male-dominated and, unfortunately, there’s still sexism and gender bias in any workplace, especially ones such as physics and tech. Surprisingly, having now worked in both industries, I have experienced more gender bias and discrimination in tech than I did in physics. When I explain that I am the CTO of a tech company, people often react in a very surprised manner. In physics, I never actively noticed anyone being stunned about the fact I was a particle physicist.

We still have a long way to go until women represent a relatively equal part of the workforce in these industries. However, I’d like to think that I can contribute to these efforts. I’m very proud to have some of the people who worked on the Higgs Boson discovery as part of my team at Natural Cycles now, and as a company, we have a rough split of 64 per cent female and 36 per cent male colleagues. Despite such challenges, we’re starting to see more and more greatly talented women in physics. One of my esteemed role models is Fabiola Gianotti – the Director General of CERN.

From physics to fertility

I decided to leave physics in 2013 when the LHC (Large Hadron Collider) was shutting down for two years. With the discovery of a new particle being so rare, I thought that if I were ever to consider trying something new, that this would be the time. While the very first version of the algorithm was intended for personal use (we were trying to solve our own need regarding the need for an effective, natural method of contraception), it was my husband’s idea to package the algorithm into an app, with the aspiration that more women and couples could benefit from what we could offer. I was sad to leave physics and the incredible team I worked with, but it helped to know that my knowledge and experience in physics would be essential to making Natural Cycles a success. Physics has played a very crucial part in the development of Natural Cycles; if I hadn’t had my experience as a researcher at CERN, I would not have been able to develop the algorithm.

To develop the algorithm I used similar statistical and programming techniques to those used for the Higgs Boson research. The main difference is the type of data I now perform research on, which represents information on women’s fertility and reproductive health, rather colliding particles. The need for such knowledge and expertise is what led me to employ five talented ex-CERN particle physicists, who are part of our innovation team in Geneva. Their job is to analyse all the data we have to create new algorithms to continue innovating within the field of women’s health.

How medical device CEOs can navigate digital health disruption

In the first of a series of three articles, we get global leaders, McKinsey & Company's insight on the medtech market right now. They give their expert advice to medical device companies, explaining how they can navigate through digital disruption.


The algorithm has come a long way from the very first iteration (we still optimise it once per year, with more data, to make it even smarter) and gaining approval for Natural Cycles as a medical device marked a key milestone for us. To achieve this, we carried out several clinical studies to prove the effectiveness of the method. Our CE mark (granted by the German regulatory body, Tüv Süd, for medical devices) is based on mandatory scientific evidence that demonstrates a 93 per cent typical use effectiveness rate, from a study of over 22,000 women. To gain US Food and Drug Administration (FDA) clearance, an additional data analysis of more than 15,000 women was carried out which showed that Natural Cycles demonstrated a typical use Pearl Index of 6.5 (equivalent to a 93 per cent effectiveness rate, when rounded up). These regulatory clearances, however, are not only based on our clinical studies; we were required to demonstrate that our company processes were robust enough to ensure consistent, high-quality standards, from how we hire and train employees to how we test and release new versions of the app.

The journey has been more challenging than first expected. Perhaps naively, I expected that if I created a product that could benefit so many people and simultaneously provided greater contraceptive choice, that it would take off. I have come to realise that it’s not that simple. We have received some resistance from both the medical community and journalists due to scepticism and misunderstandings around our revolutionary merger of women’s health and technology. We’ve learnt a lot from all of this. I now understand that if one does something innovative, there will always be challenges along the way. Reading the amazing app reviews from our users on a daily basis keeps our motivation up – one thing I love to hear about is how Natural Cycles benefits women around the world.

Elina Berglund

A vision for the future

We have seen limited innovation in the contraceptive field, and there are currently only a few players in this area. One of the main barriers to innovation is that enormous investments are required to develop and launch a new product into such a regulated the market. Women’s health is a field that has been under-developed and under-researched. Many diagnoses that are very common for women have been taboo to talk about and difficult for doctors to diagnose. What I hope to see in the future is more innovation in not only contraception but in women’s health generally as there’s so much that technology could do in this space.

Within the next five years, I want to see data-driven solutions that enable us to make smarter decisions for our bodies, and that support us to take preventative action to support ongoing health and wellness. I hope to see more digital players with clinical research and regulatory certification backing up their claims, to make it easier for customers to distinguish between products. Until now, there has not been a requirement for apps to comply with any regulation. However, we hope to have been part of a change and to have begun to pave the way as the first certified contraceptive app. I think this is a necessary step to increase both quality and trust in the field. If research could be undertaken on all the data that companies collect and share through publications, I believe we could make the world a better place. Natural Cycles will most definitely continue to innovate in the field of women’s health, and follow our mission of ‘pioneering women’s health with research and passion’, – it’s in our DNA.

About the author

Journalist and editor Kathryn Reilly has worked in consumer, contract and medical writing for more than 20 years.

Related articles


You're the expert! Write for The Engine or share your articles, papers and research

Add your content

Add your content

Keep informed

Sign up for Ignition, our regular, ideas-packed newsletter

Sign in with social media

or with a username