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Scientific research at Clue

How tracking your cycle advances female health

This article was originally published February 24, 2020 and a second edition was published on July 21, 2022.

When you track in Clue, your de-identified data becomes something powerful: data that can help answer questions to better understand menstrual and reproductive health, and ultimately, to improve healthcare. Women and people with periods have historically been underrepresented in health research, and we believe Clue data presents an important opportunity to change this.

Your cramps, cravings, and the other categories you track become part of an unprecedented data set that can be used by top research institutions and clinicians to explore topics with real-world impact. This research can help scientists better understand our bodies, explore cultural and demographic diversity, and break harmful taboos.

Protecting private health data is everything

Ensuring the protection of your private data is our highest priority. We never sell data. We only share data that is directly relevant to the research question and follow strict protocols to ensure it is de-identified, meaning researchers only work with anonymous data that cannot be traced back to any individual person. 

  • We remove all personal identifiers such as name, email address, or IP address.

  • We then take additional precautions to ensure that identities can’t be inferred, such as: 

    • ensuring there are a sufficient number of users that have the same general characteristics (e.g. there must be at least 100 users in the same city within the same age range and with the same most recent contraceptive method);

    • rolling data into buckets where possible (e.g. using age or weight ranges rather than specifics);

    • shifting tracking dates when actual dates aren’t necessary to the research question.

You can read more about how Clue handles your data in our Privacy Policy.

Our criteria for research partnerships

We only work with carefully chosen researchers to explore important research questions, with the goal of publishing the results in scientific journals. When choosing to partner with researchers from recognised research and academic institutions, we take care to ensure each project meets the following strict criteria:

  1. It aims to answer specific scientific questions that promote understanding of topics relevant to Clue users and all people with cycles.

  2. It is scientifically and ethically sound, novel, and innovative.

  3. It adheres to strict data protection requirements in accordance with the EU’s General Data Protection Regulation (GDPR).

Different types of research you can participate in

As a Clue user, there are many different ways you can help advance research:

  1. Contribute the data you track in Clue: Consenting to the use of your tracked data for research purposes means your de-identified data can be used to answer important menstrual and reproductive health questions. 

  2. Take surveys in Clue: You may occasionally receive an in-app message asking if you would like to take part in a survey, which might be the survey alone or combined with your de-identified data tracked in Clue. There will always be an introduction screen explaining the study and what data will be used, which you can review before you agree to participate.

  3. Participate in a clinical study that uses Clue to collect data: Researchers can use Clue to collect menstrual cycle data for their studies. For example, if a researcher is investigating how exercise impacts menstrual bleeding, their study could have participants engage in different exercise programs while using Clue to track their periods and other symptoms. You might see these types of studies promoted by Clue and you can enroll in a study directly with the research team.

  4. Participate in a study promoted by Clue: While having a diverse group of research participants is critical to understanding health in different populations, it can be very challenging to recruit people from wide ranging backgrounds. You might see research studies related to sexual or reproductive health promoted in the Clue app or Clue social media that you can participate in.

With the help of our Science and Data Teams, our academic collaborators are exploring questions like: Does air pollution affect menstrual patterns? How does exercise impact teenagers' periods? How might our menstrual and symptom patterns help us spot disease and illness risk earlier? 

If you are a researcher interested in collaborating with us, you can reach out to our team at research@helloclue.com

Explore Clue’s research collaborations

The following is a snapshot view of just some of the work carried out through our current and past research collaborations.



Did the COVID-19 pandemic impact menstrual cycles?

Institution: University of Montpellier (CNRS), Oregon Health & Science University, Johns Hopkins University (related but independent projects) 

Lead researchers: Alexandra Alvergne PhD (CNRS);  Alison Edelman MD, MPH (OHSU), and Mostafa Borahey MD, PhD, MBA (JHU)

While there has been anecdotal evidence from people experiencing menstrual cycle changes (such as longer cycles or heavier periods) after COVID-19 infection or vaccination, there have been few studies on the topic. This project paired survey data on COVID-19 infection and vaccination dates with menstrual cycle data from Clue, in order to evaluate any potential effects of each. This is one of the few studies on the pandemic and menstrual cycles to utilize real-time tracked data instead of just recalled experiences, strengthening the study quality. 

Read more

Associations Among Menstrual Cycle Length, Coronavirus Disease 2019 (COVID-19), and Vaccination

How do different people experience ‘heavy menstrual bleeding’?

Institution: Clue in partnership with the Bill and Melinda Gates Foundation

Lead researchers: Amanda Shea PhD and Virginia Vitzthum PhD

Heavy menstrual bleeding (HMB) is estimated to impact around 30% of women, but it is often under-recognized and difficult to diagnose as each individual may have a different understanding of ‘heavy’ menstrual flow. This project compared Clue users’ tracked bleeding with their responses to an online questionnaire and found that for people who reported having a heavy period, actual flow heaviness was not always the most important factor in characterizing their period. In fact, some people who said they had heavy periods did not track any days of heavy bleeding. Period 'heaviness' was associated with not only increased period length and number of days with heavy flow, but also with increased pain and other physical symptoms such as fatigue and digestive issues. Those who reported heavy periods also reported a greater disruption of daily activities such as the ability to participate in sexual activity, social and leisure activities, and school or work. 

Read more

More than blood: app-tracking reveals variability in heavy menstrual bleeding construct

How do sleep and stress impact teens’ menstrual cycles?

Institution: University of California, Berkeley

Lead researcher: Kim Harley PhD

Using Clue tracking data and surveys from approximately 10,000 Clue users, Dr. Harley and her team are examining how sleep patterns, stress, and social support, as well as behaviors such as exercise, smoking, and alcohol use, impact cycle characteristics in 13-19 year-olds. Ultimately, they hope to learn more about which factors impact menstrual cycles in young people, thereby potentially influencing their long term health.

Can air pollution affect the menstrual cycle?

Institution: Senseable City Lab at Massachusetts Institute of Technology (MIT) 

Lead researchers: Priyanka deSouza PhD and Fabio Duarte PhD

By focusing on specific cities and combining data on local air quality with Clue menstrual cycle data from the same geographic areas (Clue does not collect specific location data and has only approximate city-level data), this project aims to help understand how environmental factors can contribute to reproductive health. The researchers are also interested in whether acute air pollution spikes, caused by events such as wildfires, can affect cycle length and variability of those exposed to these events. This project is focused on cities in Brazil, Mexico, and the United States.

Are digestive symptoms associated with mood during PMS?

Institution: Johns Hopkins University

Lead researchers: Liisa Hantsoo, PhD

Digestive symptoms such as bloating, constipation, and nausea are experienced before menstruation by as many as 73% of people with cycles. Associations between digestive symptoms and mood are poorly understood among those with premenstrual syndrome (PMS), although previous studies suggest that the two may influence each other. This study is investigating the frequency of digestive symptom tracking across the cycle as well as the relationship between digestive symptoms and mood symptoms such as feeling stressed, withdrawn, and unmotivated during the premenstrual period. 

What is the contribution of menstrual cycles to mood, behavior, and vital signs? 

Institution: Stanford University

Lead researchers: Emma Pierson PhD and Jure Leskovec PhD

This project aimed to better understand how dimensions of mood, behavior, and vital signs vary daily, weekly, seasonally and/or during menstrual cycles, using Clue's rich dataset combined with machine learning models. The research team hopes that this work can improve understanding of how menstrual cycles contribute to overall health.

Read more

Modeling Individual Cyclic Variation in Human Behavior

Daily, weekly, seasonal and menstrual cycles in women’s mood, behavior and vital signs

How do menstrual cycle lengths and symptoms vary across individuals? Can AI be improved to more accurately predict when an individual’s next period will be?

Institution: Stanford University

Researchers: Noémie Elhadad PhD, Kathy Li PhD, Iñigo Urteaga PhD, Chris Wiggins PhD

Examining cycle length alone is often not enough to capture the full extent of menstrual cycle variation. Dr. Elhadad’s team looked at cycle variability (how much a person’s cycle lengths change from cycle to cycle) and its association with symptom tracking patterns (such as headaches and tender breasts). Further investigation of these differences could help clinicians and researchers better understand the wide range of cycle patterns that people experience and more effectively use cycle characteristics as potential health indicators. 

For a separate project, Dr. Elhadad’s team aimed to differentiate menstrual patterns from app tracking behavior. When people forget to track their periods in period tracking apps, the data appears as an inaccurately long cycle, which can affect the app’s predictions. By finding ways to estimate when a long cycle might actually be due to forgetting to track, more accurate models can be developed to provide better estimates of the timing of future cycles. Dr. Elhadad’s team developed a model that determines the probability of an individual forgetting to track their cycle, which can be used to improve app experiences and data quality for research.  

Read more

A Predictive model for next cycle start date that accounts for adherence in menstrual self- tracking

A Generative Modeling Approach to Calibrated Predictions: A Use Case on Menstrual Cycle Length Prediction

Characterizing physiological and symptomatic variation in menstrual cycles using self-tracked mobile-health data

Is there an association between menstrual patterns and chronic disease risk? 

Institution: Mailman School of Public Health at Columbia University

Lead researchers: Mary Beth Terry PhD, Jasmine McDonald PhD, and Lauren Houghton PhD

Breast cancer is estimated to affect approximately 280,000 women per year in the USA alone. Prior research suggests that there may be a link between menstrual cycles and breast cancer risk, but there is little longitudinal data to evaluate this link. Dr. Terry and her team are trying to better understand how menstrual cycle characteristics may be linked to breast cancer. To do this, study participants from the Breast Cancer Family Registry, will use Clue for long-term tracking of their menstrual cycle symptoms, enabling researchers to collect real-time data on a daily basis. As breast cancer can be more effectively treated when caught early, this research aims to determine if there are any menstrual cycle symptoms or patterns that can be used to support early detection.

Do STIs influence premenstrual symptoms?

Institution: Oxford University

Lead researcher: Alexandra Alvergne PhD

Through a survey, Clue users were asked about recent diagnoses with any sexually transmitted infections (STI). Those who had experienced an STI, could share whether they had any symptoms and if they had received treatment. These answers were combined with the participants’ data tracked in Clue during their menstrual cycles before and after their diagnosis. 

It was found that before diagnosis, the presence of an STI doubled the likelihood of reporting negative premenstrual symptoms (PMS) such as pain (headaches, cramps) and low mood. While severe PMS may be brushed off as just part of the cycle, this research indicates it could actually be a sign of an undetected STI. This means monitoring one’s menstrual symptoms and how they change cycle to cycle could help detect and treat symptoms and conditions earlier.

Read more 

Do sexually transmitted infections exacerbate negative premenstrual symptoms? Insights from digital health

How does sexual desire change across the menstrual cycle and with contraceptive use?

Institution: Max Planck Institute for Human Development 

Lead researcher: Ruben Arslan PhD 

Despite widespread interest, there is limited research on the effect of the menstrual cycle and hormonal contraceptives on sexual desire. Even though changes in desire are frequently cited as a reason for dissatisfaction with contraceptives, there is surprisingly little strong evidence for such effects. This project aims to use data tracked in Clue to better understand how sexual desire might change across the cycle and how different contraceptive methods may affect it. These findings can help people with cycles better understand possible shifts in sexual desire and to select contraceptive methods that best meet their needs. 

Does hormonal birth control affect experiences of breast tenderness?

Institution: Stanford University

Lead researchers: Laura Symul PhD and Susan Holmes PhD

Breast tenderness is a commonly reported menstrual cycle-related experience. This project is using Clue app-tracked data to investigate how experiences of breast tenderness change across each cycle, if these patterns are specific to individuals, and if they are affected by use of hormonal contraceptives. 



Do patterns in sexual activity or fertility shape birth seasonality?

Institution: Stanford University

Lead researchers: Laura Symul PhD and Susan Holmes PhD

Why are more babies born at certain times of the year? Understanding birth seasonality has broader implications for fertility planning, infant and maternal mortality, and healthcare systems. Determining if these changes are a result of variability in when people are having sex or when they are most fertile (or other factors altogether) has historically been difficult to test without large-scale data on sexual activity. This study analyzed birth records along with data on sexual activity from half a million Clue users from both the Northern Hemisphere (UK, US, and France) and the Southern Hemisphere (Brazil).

Read more

Unmasking Seasonal Cycles in Human Fertility: How holiday sex and fertility cycles shape birth seasonality 

How well can menstrual tracking apps predict pregnancy?

Institution: Stanford University

Lead researchers: Emma Pierson PhD, Jure Leskovec PhD

This study investigated the feasibility of using app-tracked data, such as when a person has protected or unprotected sex during a cycle, to determine the probability of becoming pregnant.  Using data from over 65,000 Clue users, the researchers developed models that were able to learn that having unprotected sex near the middle of the cycle is most likely to result in pregnancy. This is consistent with previous fertility research findings that unprotected sex in the fertile window leads to the highest likelihood of pregnancy, illustrating the potential for building algorithms that can provide useful predictions to app users.

Read more 

Predicting pregnancy using large-scale data from a women's health tracking mobile application



How do people use mobile technology for sex-related purposes?

Institute: Kinsey Institute

Lead researchers: Amanda Gesselman PhD and Virginia J. Vitzthum PhD

Using a survey sent via the Clue app, this project gathered 130,885 responses from people in 191 countries to assess how women around the world interact with mobile technology for sex-related purposes (such as to find sexual partners, learn about sex and improve their sexual relationships, and track their own sexual health), and how gender inequality in the country of residence may influence the use of this technology. Staying connected with a partner when apart was the primary use of sex-tech, and self-education was particularly important in countries with low gender equality. These findings may inform large-scale targeted studies, interventions, and sex education to improve the lives of people with cycles around the world.

Read more 

Mobile sex-tech apps: How use differs across global areas of high and low gender equality

How does menses impact attitudes and behaviors around condom use?

Institute: Kinsey Institute

Lead researchers: Cynthia Graham PhD, Stephanie Sanders PhD, Virginia J. Vitzthum PhD

Kinsey’s trailblazing Condom Use Research Team (CURT) worked with Clue to conduct the largest-ever study of women’s attitudes and behaviors around condom use during menses. Over 110,000 responses from Clue users around the world were used to examine 1) the prevalence of condom use during menses, 2) reasons for condom use (STI protection vs pregnancy prevention vs partner protection from blood), 3) if condom use during menses varied depending on age and gender inequality of country of residence, and 4) whether age and gender inequality of country of residence interact with reasons for using, and not using, condoms during menses. This study aimed to help researchers and practitioners better understand condom use attitudes and behaviors in order to inform the development of more effective education programs and interventions.   .

Read more  

Decision making over condom use during menses to avert sexually transmissible infections

A Cross-Country Comparison of Reasons for Condom Use during Menses: Associations with Age and Gender Inequality

What are people looking for in an ideal romantic partner?

Institute: University of Göttingen 

Lead Researchers: Tanja M. Gerlach PhD, Laura J. Botzet PhD, and Virginia J. Vitzthum PhD

What people want in a romantic partner has long fascinated researchers (and the general population). To explore this question, surveys were sent via Clue and myOne (a condom company), collecting responses from over 64,000 people from 180 countries. From these responses, the research team aims to better understand what people are looking for in potential long- and short-term partners and how these preferences change with factors like age. 

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Live in sync with your cycle and download the Clue app today.