“Many fertility algorithms limit accuracy by using last month’s ‘weather’ to predict what will happen this month, and can only tell you for sure that you were fertile after the fact. – lead author, Azure Grant

Researchers in the Kriegsfeld Lab at the University of California, Berkeley (UCB), in collaboration with Precision Analytical and Oura, have published the results of QCycle, a project aimed at identifying signals that can predict female fertility. The researchers were looking for signs of the LH surge, a sudden hormone increase that acts as the “go signal” for the release of an egg (ovulation).

The QCycle team discovered that by looking at Oura Ring patterns for the first 1-2 weeks of the menstrual cycle, they could anticipate the LH surge days in advance for 100% of participants.

The Oura Ring was able to detect changes in heart rate variability (HRV) and daytime skin temperature that signal an upcoming LH surge.

The lead author of the study, Azure Grant, shares the need for this kind of research: “Many fertility algorithms limit accuracy by using last month’s ‘weather’ to predict what will happen this month, and can only tell you for sure that you were fertile after the fact.”

For example, traditional fertility awareness tools face timing challenges when identifying your LH surge. These tools try to estimate when the LH surge will occur based on previous months’ oral temperatures, identify that the LH surge is already in progress using a hormone test, or retrospectively confirm that ovulation occurred with a sonogram.

By contrast, QCycle shows that it is possible to forecast the LH surge in advance, non-invasively, with a tool like the Oura Ring that provides personalized and continuous temperature data. The results of this study pave the way for more accurate methods of cycle tracking and natural family planning by showing us the power of understanding what’s happening in our bodies as it happens.

The full paper can be found in the journal Scientific Reports.

For those interested in how these findings impact women’s health research, read on.


Read more about the LH surge and other phases of the menstrual cycle.


How Did QCycle Empower Women?

QCycle was an innovative form of “participant-led” research where the women generating the data were active contributors to the study. Women from the Quantified Self community joined QCycle via an organization called Open Humans. Open Humans enabled the participants to share discoveries and learn about themselves in-depth while providing direct Oura data access to the researchers. In total, 25 women — representing a variety of cycle lengths, cycle regularity, ages, and perimenopausal symptoms — joined the study to contribute Oura metrics, LH surge test results, and personal observations. Additionally, the participants generated daily hormone data via an innovative form of urine testing called “Dutch Test”.

This open collaboration between a curious community, a non-profit, private companies, and a university enabled the participants to pursue personal questions while contributing to a scientific discovery.

What Patterns Did They Discover?

QCycle leveraged the Oura Ring as the only consumer wearable to generate research-grade, minute-by-minute temperature readings and an unparalleled high sampling rate of 250Hz for nightly resting heart rate (RHR) and heart rate variability (HRV). Having access to such strong, continuous streams of data enabled the researchers to go beyond measuring averages (e.g., 98 degrees, 50 bpm) to start analyzing subtle, wavelike patterns in moment-to-moment data known as “ultradian rhythms.” These patterns can only be monitored with data points taken at fast intervals (e.g., every 5 minutes) like the Oura Ring.

If you have ever noticed that your hunger comes and goes throughout the day or that you have “bouts” of energy rather than a steady stream, what you are sensing are your ultradian rhythms. These wavelike patterns of hormones, body temperature, breathing rate, neurotransmitters, heart activity, and more repeat every few hours. The pattern of these waves gives us information about our bodies and, in this case, helps identify key events in female fertility:

  • Pre-Ovulation:  Leading up to ovulation, the body produces larger and more regular ultradian temperature and HRV wave patterns. The study used the Oura Ring to spot the start of that process (Clue 1) as well as when temperature and HRV waves are at their biggest and most regular (Clue 2).
  • Perimenopause: In women approaching menopause (perimenopausal) these HRV and temperature wavelike patterns became more variable.

Innovative fertility research

How Do These Discoveries Impact You?

In the future, this kind of research can improve the tools available to consumers.

Professor Kriegsfeld, senior author on the the study, commented on the implications of the findings:

“We were really excited to see our preclinical work on the neural and hormonal mechanisms underlying ovulation translated into a promising and convenient method of fertility prediction.  The findings highlight how medically accurate devices like the Oura Ring can be used to conveniently collect high-resolution data that enables women to monitor and anticipate future changes in their reproductive physiology.”   

Azure Grant adds how accurate cycle information can make a difference: “A tool that can help you get ahead of ovulation, simply by wearing a ring, is incredibly useful. Many of us were not taught how our menstrual cycles can affect metabolism, sleep, or thinking. It isn’t only about family planning, it’s about having a better idea of how you could feel your best on the day of the job interview, when you might do your hard workouts, or when you might feel most creative. Having accurate, up-to-date information could give you more agency in planning both the minor and major decisions in your life.” 

It’s about changing the way we think about our cycles.

“Fertility prediction is like weather forecasting in need of a major upgrade. The ‘weather patterns’ are the events of the menstrual cycle that influence one’s life planning.  Many fertility algorithms limit accuracy by using last month’s ‘weather’ to predict what will happen this month and can only tell you for sure that you were fertile after the fact. If the meteorologist required you to set up your own weather station, only told you when it was already raining, and if every time they guessed wrong you risked an unplanned pregnancy, then they’d be out of the job! The situation for female reproductive health is a lot like this. Natural family planning or cycle tracking currently requires a lot of careful effort by the end user and doesn’t offer accurate enough predictions. 

We can do better…. There are huge potential benefits to women, and to society, if we can improve these methods and provide education about them”.

What Happens Next?

Oura is committed to helping pursue solutions on the cutting edge by ensuring that research is expanded and validated to represent our diverse user base.

Research like QCycle paves the way for tools like Oura to move towards more personalized, current, and accurate ways of tracking the menstrual cycle. While Oura doesn’t currently have a cycle tracking feature, we are actively working with researchers and users alike to understand how Oura data can help people monitor their ovulatory cycles, birth control methods, pregnancies, hormone status, post-partum life, and more.

Research like this helps inform our teams and could certainly impact the features we bring to market in the future. We are eager to carry out that work with you – the Oura Community, so that these results can be tested in a larger, more diverse population.

In The Meantime, Learn From Our Community: