MIT, University of Colorado Denver, and Clue App Publish Largest Women’s Health Study Documenting Air Pollution’s Impact on Menstrual Cycles
Researchers at MIT’s Senseable City Lab and the University of Colorado Denver, in collaboration with the Clue app, have published the largest study of its kind examining the impact of air pollution on menstrual health across multiple countries. The research, just published in The Lancet Planetary Health, analyzed data from 2.2 million menstrual cycles tracked in Clue, across 230 cities in the United States, Mexico, and Brazil. The study found that higher concentrations of fine particulate matter (PM2.5) in the air correspond with increased frequency of menstrual cycle irregularities.
While air pollution research has traditionally focused on respiratory or cardiovascular effects, impacts specific to women’s health have been largely overlooked— a reflection of the persistent gender health gap in scientific research. This study brings women’s health into focus, revealing how environmental factors influence menstrual cycles in unexpected ways, while also demonstrating that when researchers examine sex differences, they can uncover critical health effects that might otherwise remain invisible.
Specifically, the study found that long-term exposure to higher levels of fine particular matter (PM2.5) is associated with a higher percentage of abnormal menstrual cycles, particularly longer cycles, a potential sign of disrupted endocrine and reproductive functioning. The study demonstrated that data from cycle tracking apps can be used to answer important questions on the impact of environmental factors on menstrual and reproductive health.
“Menstrual cycle length and variability are a vital indicator of women’s health. Research has shown that highly variable menstrual cycles can be associated with an increased risk of premature mortality, cardiovascular disease, type 2 diabetes, cancer, and infertility. The impacts of pollution on menstrual cycle length have been understudied, as few epidemiologic cohorts track menstrual cycle information.” Says Priyanka deSouza, PhD, MSc, MBA, MTech.
“This study gives us a unique look at how air pollution might affect menstrual cycle length in three different countries. The researchers used data from the Clue app to evaluate long and short cycles in the same person, in relation to air pollution levels in their city. The results suggest a link between PM2.5 (a type of air pollution) and cycle length. PM2.5 is already known to harm human health, especially the heart and lungs. This study shows that it may also affect ovulation and menstrual health.” Comments Shruthi Mahalingaiah, MD, MS, Harvard T. H. Chan School of Public Health and Massachusetts General Hospital.
How Clue’s Tracking Technology Can Advance Reproductive Health Science
Rather than relying on retrospective self-reporting as previous studies have done, the research for this study utilized longitudinal cycle tracking data from Clue users, combined with satellite measurements of air pollution levels. This study underscores the power of digital health tools, such as the Clue app, to surface meaningful population-level patterns—especially in areas where traditional research has fallen short.
“Dealing with personal and sensitive data always poses ethical challenges. In this study we were very careful in dealing with such data sets, but we were able to highlight how environmental stressors can have such deep and personal effects,” says Fábio Duarte, of MIT Senseable City Lab.
“Clue is helping close the gender health gap by making large-scale research into women’s health faster and more feasible than ever before,” said Amanda Shea, Fractional Chief Science Officer at Clue. “By analyzing millions of de-identified cycles tracked in the app alongside environmental data, we’ve taken a new approach to exploring how external factors like pollution might influence reproductive health. This kind of research offers people meaningful insights into their bodies, helping them recognize patterns earlier and make more informed decisions about their health.”
Further Research and What Women Can Do
This research builds on prior toxicological and epidemiologic work linking air pollution to reproductive outcomes like preterm birth and infertility, but fills a critical gap by focusing on menstrual health—an under-researched indicator of overall well-being. These findings reinforce calls for improved air quality standards and environmental justice for communities most at risk.
While further research is needed to confirm these effects and better understand the biological mechanisms behind them, especially as the climate crisis intensifies and pollution persists, advancing understanding of how environmental factors impact women’s health is more important than ever.
For those concerned about air quality’s potential impact on their health, Clue’s science team recommends that they:
Consult healthcare professionals: Talk to your healthcare provider if you have any concerning cycle changes or are experiencing symptoms that impact your quality of life. Sharing your cycle tracking data can help inform these discussions.
Monitor air quality and limit exposure during high pollution days: In many cities, you can check daily air pollution levels in your area through local environmental agencies or air quality monitoring apps. Limiting outdoor exposure when air pollution levels are high can help protect your health.
Use the Clue app to track your cycle: By tracking your periods and related cycle symptoms over time, you can build a clearer picture of what’s typical for your body. Understanding your own patterns makes it easier to spot changes early—so you can take action or seek support when something feels off.