Scientific research at Clue

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, contributing to improved healthcare and ultimately, better female health. 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 a research question and follow strict protocols to ensure it is de-identified, meaning that researchers are not able to link data back to any individuals. 

• 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).

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Different types of research you can participate in

As a Clue user, there are many 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. Surveys can be taken anonymously or could be 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 on Clue social media that you can participate in.

Explore Clue’s research collaborations

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

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

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RESEARCH ON THE MENSTRUAL CYCLE

Did the COVID-19 pandemic impact menstrual cycles?

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

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. These projects are amongst the few studies on the pandemic and menstrual cycles to utilize real-time tracked data instead of recalled experiences, strengthening the study quality. The study found a small, temporary increase in menstrual cycle length following a COVID-19 infection or vaccination. In both cases, users’ cycle length reverted to their previous average after one cycle. 

Read more

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

The association of COVID-19 vaccination and menstrual health: A period-tracking app-based cohort study

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. This supports the recent shift away from blood volume measurement to a focus on quality of life when evaluating heavy menstrual bleeding. It also highlights the importance of understanding individual experiences and goals when providing healthcare.

Read more

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

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 combining data on local air quality with Clue menstrual cycle data from the same geographic areas, this project aims to build on our understanding of how environmental factors like air quality can impact menstrual health, including cycle characteristics like cycle regularity and bleeding heaviness. The researchers are also investigating how acute air pollution spikes, caused by events such as wildfires, can affect cycle length and variability of those exposed. This project is focused on cities with varying average air quality in Brazil, Mexico, and the United States.

Are digestive symptoms associated with mood during PMS?

Institution: Johns Hopkins University

Lead researcher: 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 applied machine learning models to Clue cycle tracking data to better understand how various dimensions of mood, behavior, and vital signs are differentially affected by different cycles including daily, weekly, seasonal and menstrual cycles. This aims to build our 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 help us more accurately predict when an individual’s next period will be?

Institution: Stanford University

Lead 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 examined 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 their app, 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

Do STIs influence premenstrual symptoms?

Institution: Oxford University

Lead researcher: Alexandra Alvergne PhD

Experiences of premenstrual symptoms vary between individuals and can also differ from cycle to cycle for the same person. Little is known about what factors can influence these experiences, including what impact sexually transmitted infections (STI) may have. Clue users were surveyed about recent STI diagnoses, what symptoms they had, and if they had received treatment. These answers were combined with menstrual cycle experiences tracked in Clue during the 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 such as pain (headaches, cramps) and low mood. While severe premenstrual symptoms 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 potential underlying 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 Lennartz 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 evidence for such effects. This project aims to use data tracked in Clue to better understand how sexual desire changes across the cycle and how different contraceptive methods may affect it. These findings can inform our understanding of cycle-related changes and provide insight into potential contraceptive side effects. 

Does hormonal birth control affect experiences of breast tenderness?

Institution: Stanford University

Lead researchers: Laura Symul PhD and Susan Holmes PhD

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

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RESEARCH ON THE MENSTRUAL CYCLE AND LIFE PHASES

How do exercise and stress impact teens’ menstrual cycles?

Institution: University of California, Berkeley

Lead researcher: Kim Harley PhD

Despite the American College of Obstetrics and Gynecology declaring the menstrual cycle a vital sign for adolescents, there is little research on the variation in teen cycle patterns across the population or on how they change in the years after menarche (the first period). There is also limited information on how factors like exercise and stress may impact cycle experiences.  Using surveys and cycle tracking data from nearly 10,000 Clue users aged 13-18, this project characterized cycle patterns among adolescents and how they differed by age and age of first period. Subsequent publications will explore how sleep patterns, stress, and social support, as well as behaviors such as exercise, smoking, and alcohol use, impact cycle characteristics in adolescents. This research will expand understanding of teen cycles, which can enhance our ability to detect and treat abnormal cycle patterns earlier, ultimately improving long-term health for people with cycles.

Read more

Menstrual Cycle Characteristics of U. S. Adolescents According to Gynecologic Age and Age at Menarche

What symptom patterns are experienced by people in perimenopause?

Institution: University of California, Berkeley

Lead researchers: Kim Harley PhD and Lindsay Parham PhD

Menopause, or when periods stop, is an inevitable part of life for people with cycles. The transition to menopause, known as perimenopause, is characterized by fluctuating hormone levels, variable cycle lengths, and a wide array of symptoms such as hot flashes, mood changes, and sleep problems. Despite being such a significant life phase, research on perimenopause is lacking, with little known about when each individual may enter perimenopause, how long it will last, what unique array of symptoms they might expect, and what factors might influence these symptoms. This study will use Clue cycle data, surveys, and biometric data from the Oura ring to better understand the range of symptom patterns people experience and how they change throughout the perimenopause journey. This can help researchers and clinicians to better understand perimenopause, unlocking opportunities to provide better resources, tools, and guidance to support those who are navigating through this transition.

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RESEARCH ON HEALTH CONDITIONS

Can self-tracked menstrual patterns be used to detect endometriosis?

Institution: Massachusetts Institute of Technology

Lead researchers: Aparna Balagopalan, Cassandra Parent, and Marzyeh Ghassemi PhD

Endometriosis is a chronic condition where endometrial-like tissue grows outside of the uterus, causing extreme pain and sometimes even leading to infertility. Endometriosis affects roughly 10% of people with cycles, but because symptom patterns can be wide ranging and often overlap with other conditions, it still takes an average of 6–11 years to get a diagnosis. This study will apply machine learning approaches to cycle experiences tracked in Clue by those with and without an endometriosis diagnosis, to see whether it is possible to identify those with endometriosis based on their symptoms alone.

How are heavy and painful menstrual periods related to depression?

Institution: University of Exeter and University of Bristol

Lead researchers: Gemma Sharp PhD and Jon Heron PhD

While heavy menstrual bleeding, menstrual pain, and depression are very common, not much is known about their relationship. People with heavy and/or painful menstrual periods are thought to be at an elevated risk of depressive symptoms. In addition, depressive symptoms and psychological stress can disrupt features of the menstrual cycle. This study will use menstrual cycle experiences tracked in Clue to better understand patterns in experiences of heavy bleeding and pain, both with and without clinical depression or depressive symptoms, as well as how these patterns change with age. This could help healthcare providers identify those who may be at higher risk of heavy and painful periods and cycle-associated depressive symptoms, providing an opportunity to implement interventions sooner. Ultimately this can help improve the mental health and wellbeing of people with cycles.

Do focus, attention, and motivation change across the menstrual cycle among those with and without ADHD?

Institution: Queen Mary University of London

Lead researcher: Jessica Agnew-Blais PhD

It is well known that mood can be affected by menstrual cycle-related hormone fluctuations. How feelings of focus, motivation, or other aspects of mental functioning may be affected are, however, less well studied. There are reports of symptoms worsening across the cycle in those with conditions like attention-deficit hyperactivity disorder (ADHD), but very little research has been done to characterize and quantify this, leaving those with the condition with limited options for improving their symptoms. This study will use cycle experiences tracked in Clue by those with and without ADHD diagnoses, to examine cycle patterns for things like motivation, focus, and productivity, and how they differ between the two groups. This can expand our understanding of cycle-related mental changes, which could help improve clinical practice for the evaluation and treatment of  ADHD and better support those with the condition. 

Can menstrual cycle tracking help us better understand experiences of PMDD to improve the diagnostic criteria?

Institution: Cardiff University

Lead researchers: Chloe Apsey and Arianna Di Florio PhD

Premenstrual dysphoric disorder (PMDD) is estimated to impact 1–6% of people with cycles and is characterized by severe emotional, behavioral, and physical changes in the days leading up the period. While awareness of PMDD has improved in recent years, there are still conflicting views around the definition and diagnosis of PMDD. Clue provides an opportunity to examine what symptoms those with PMDD track each day of the cycle as well what other conditions those with PMDD have also been diagnosed with. By mapping symptom patterns and co-morbidities in those with and without a PMDD diagnosis, this study aims to expand knowledge about the condition and inform discussions on the diagnostic criteria for PMDD, ultimately endeavoring to support more effective screening and treatment of those with the condition.

How does the menstrual cycle impact mood and energy levels in those with or without health conditions?

Institution: Washington University in St. Louis

Lead researcher: Hillary Anger Elfenbein

Women frequently report changes in functioning across the menstrual cycle, but due to the frequent focus on the premenstrual phase there have been few comprehensive studies documenting changes across the whole cycle, and even less on how these changes may be influenced by the presence of related health conditions such as depression and anxiety. This study will evaluate cycle patterns of subjective functioning, and how they differ between those with and without diagnosed mental health conditions. This will strengthen our understanding of these health conditions as well as the risk of experiencing cycle-related changes, which could support the development of more effective treatment options and ultimately the well-being of those experiencing burdensome cycle symptoms.

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 connection. To investigate how menstrual cycle characteristics may be linked to breast cancer, 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.

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RESEARCH ON FERTILITY

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

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RESEARCH ON CONTRACEPTION

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

How do menstrual bleeding preferences impact contraceptive decision-making?

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

Lead researchers: Amanda Shea PhD and Virginia Vitzthum PhD

Menstrual bleeding preferences can vary greatly - while some prefer to have regular periods, others would rather skip them whenever possible. Thus, the impact of some birth control methods on menstrual bleeding frequency and duration are considered a benefit by some, but a nuisance by others. To better understand this relationship, 4,255 Clue users in the USA, India, and South Africa were surveyed and grouped based on whether they were using hormonal birth control (HBC) vs non-hormonal methods. In all three countries, non-hormonal method users were more likely to want to maintain their natural menstrual cycles and have regular periods as compared to HBC users, who tended to prefer less frequent bleeding. US-based participants had the biggest differences in bleeding perspectives between groups, with non-hormonal method users tending to have more positive associations with their periods, such as good health, fertility, and keeping in touch with their bodies. Conversely, HBC users were more likely to view periods as an inconvenient bodily function with limited personal significance. These patterns reflect differences in personal values and cultural norms and highlight the necessity of acknowledging individual goals and preferences and not taking a one-size-fits-all approach to contraceptive counseling.

Read more  

A bother or a benefit? How contraceptive users balance the trade-offs between preferred menstrual bleeding patterns and preferred contraceptive methods in India, South Africa, and the United States

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RESEARCH ON SEX & RELATIONSHIPS

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

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. 

Read more

The link between age and partner preferences in a large, international sample of single women

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RESEARCH ON APPS AND REPRODUCTIVE HEALTH

How can menstrual tracking apps support reproductive health research?

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

Lead researchers: Amanda Shea PhD and Virginia Vitzthum PhD

The underprioritization of research on people with cycles has resulted in a gaping gender data gap and inadequate healthcare for women and gender minorities. To bridge this divide, we need more effective ways to quickly and inexpensively collect health data - could apps like Clue be a solution?  Surveys were sent via the Clue app as well as through other conventional survey methodologies (including online panel providers, SMS messages, and through face-to-face interviews) to benchmark health data in three countries (India, South Africa, and the US). Data was collected on demographics, contraceptive preferences, and attitudes towards menstruation. The study found that given a sufficiently large user base, app-distributed surveys were able to quickly and cost-effectively capture large samples on par with other methods. Each method had different sample biases, but understanding what these biases are can inform strategies to mitigate them. Notably, as compared to participants of other methods, app users were more comfortable discussing their menstrual periods with others, suggesting they may be more likely to respond truthfully to questions on sensitive or taboo health topics. This work offers insight into some of the strengths and limitations of using apps like Clue in research, which can help determine when they could be a fitting tool for collecting health data. With expanding global access and use of health apps, there is a valuable opportunity to utilize these tools to enhance reproductive health research. 

Read more

Assessment of app-based versus conventional survey modalities for reproductive health research in India, South Africa and the United States: A comparative cross-sectional study

This article was originally published February 24, 2020, a second edition was published on July 21, 2022, and a third edition was published May 31, 2024.