Natural Cycles does not merely ‘claim’ to be a contraceptive — it is a CE-marked medical device

I am writing in response to Sophie Willis’ recent article, ‘Hormone hesitancy: why are women moving away from hormonal contraception?‘ (The Pharmaceutical Journal online, 26 March 2026).

While the article explores an important shift in women’s contraceptive preferences and presents views as opinion, the content does not fully reflect available evidence. Statements suggesting the Natural Cycles app is not a contraceptive method are inaccurate and risk confusing women who are seeking regulated non-hormonal options and making reproductive health decisions.

More women are seeking non-hormonal contraceptive options for different reasons, and healthcare professionals have a responsibility to provide clear, evidence-based guidance on suitable options. One such option is Natural Cycles, a regulated, non-hormonal contraceptive method^​1–3​. However, it is often misunderstood or dismissed without consideration of the clinical evidence supporting it.

At Natural Cycles, I lead a team of scientists advancing women’s health through rigorous, published clinical research. It is, therefore, important to address key statements made in the article.

Natural Cycles does not merely “claim” to be a contraceptive — the app is a CE-marked medical device, supported by peer-reviewed clinical evidence and regulatory review, designed, tested and authorised as a contraceptive in the European Union and the UK.

The Natural Cycles app is not a general period-tracking, wellness app — its NC° Fertility algorithm analyses complex, personal, biomarker data and accounts for an individual’s cycle variability. Although menstrual tracking apps include fertility predictions, they are not tested or regulated for pregnancy prevention. Conflating these tools risks misleading women.

To better understand real-world implications of relying on period-tracking apps for preventing pregnancy, our research team — alongside external collaborators from the University of Oxford and Karolinska Institute — analysed 540,000 menstrual cycles and found that predicted pregnancy risk was up to 44 times higher when using general period-tracking methods compared to a CE-marked digital contraceptive^​4​.

As a regulated medical device, we monitor real-world effectiveness and perform post-market surveillance studies. Our data consistently meet or exceed our published rates — 93% effective with typical use and 98% effective with perfect use^​5​. To use the method correctly, users must avoid unprotected sex on fertile (red) days. As with any contraceptive method, this may not be suitable for everyone. 

While Natural Cycles has been a regulated medical device in Europe since 2017, digital contraception remains a relatively new category, and we recognise there can be confusion in the medical community about how it differs from period trackers. We take seriously our responsibility to support clear understanding.

Eleonora Benhar Noccioli, vice president of science and data at Natural Cycles