Natural Cycles App Uncovers Real-World Insight Into More Than Half a Million Menstrual Cycles

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Revolutionary birth control app Natural Cycles provides a real-world insight into the characteristics of over 600,000 menstrual cycles.

Using anonymous data from real-world users of the Natural Cycles birth control and pregnancy planning app, researchers have now been able to study more than half a million menstrual cycles in incredible detail. From cycle characteristics by user age and cycle length to the validation of the estimated day of ovulation provided by the Natural Cycles app, the research has now been made available in full by Nature Digital Medicine, which serves the medical community by publishing its most significant discoveries.

In total, 17.4 million non-deviating basal body temperature measurements and 1.4 million menstrual cycles were recorded by 124,648 anonymized users of the Natural Cycles app. 80 percent of these users reported starting using the app with the intention of preventing pregnancy, while 20 percent started using Natural Cycles to successfully plan a pregnancy.

Apps such as Natural Cycles generate large amounts of data on the menstrual cycle and, provided that such real-world data can be validated against traditional clinical studies there is enormous potential to uncover new scientific discoveries.

Of 1.4 million cycles recorded by users eligible for the study, around half were excluded for reasons ranging from pregnancy to no ovulation detected. In total, 612,613 cycles were ultimately included in the study. The study was able to demonstrate cycle characteristics by cycle length, user age, BMI, and more. The study was also able to successfully provide validation of the estimated day of ovulation offered by the Natural Cycles app.

“In the study, we analyzed the key characteristics of more than 600,000 menstrual cycles,” explains Natural Cycles CEO and co-founder Elina Berglund. This comprehensive analysis of menstrual cycle parameters, Berglund says, provides important insight into the physiology of menstrual cycles among the general population, which is not widely known. “Using this large data set, our analysis reveals important information on menstrual cycle characteristics in a real-world population of women,” she adds.

One such revelation is the finding that menstrual cycles are considerably varied, with only 13 percent of women having cycles that last 28 days.

According to Berglund, knowledge and understanding of women’s menstrual cycles, fertile periods, and ovulation days is important both for individuals and for those working in the healthcare profession providing reproductive health services. “Such data is also incredibly valuable for fertility educators,” adds the Natural Cycles CEO, wrapping up, “to support education surrounding female fertility and addressing knowledge gaps across both the general public and the medical community.”

To view the full open-access article, titled ‘Real-world menstrual cycle characteristics of more than 600,000 menstrual cycles,’ first published on August 27, 2019, visit

Natural Cycles was founded by Elina Berglund and Raoul Scherwitzl, a couple who, at the time, were seeking an effective method of birth control which was non-invasive and hormone-free. Today, Natural Cycles is responsible for the first and only birth control application available for download in the United States and Europe, making the Natural Cycles app a groundbreaking piece of technology in the burgeoning digital contraceptive landscape. To find out more, head to