Does COVID-19 affect the length of your cycle?

Can a COVID-19 infection affect the length of your cycle? The outcome of Clue’s eye-opening study, in partnership with the University of Montpellier and Oregon Health & Science University, says yes. 

This study is one of many that Clue has been doing to help support female health research, using de-identified data tracked within the app. Clue’s Science Team works with renowned research institutions and universities throughout the world to advance knowledge around female health and to help close the gender health gap. 

What’s groundbreaking about this study? 

Published in August 2023, the survey was distributed over several months in 2021 and 2022. De-identified Clue user data was used to analyze the impact of COVID-19 infection and vaccinations on the menstrual cycle. Over 6,000 Clue community members contributed to the study and helped us understand how COVID-19 impacted women and people with cycles.

This was one of the first studies of its kind, powered by real-time tracked data, likely tracked at, or close to, the time of their symptoms and experiences. Previous studies relied on untracked data and memories of cycle length and changes. Published in Obstetrics & Gynecology, the official journal of the American College of Obstetricians and Gynecologists, the study was led by Alexandra Alvergne, Ph.D. from the University of Montpellier, CNRS, as well as Emily R. Boniface, M.P.H., Blair Darney, Ph.D., M.P.H., and Alison Edelman, M.D., M.P.H., from Oregon Health & Science University. 

The impact of COVID-19 on menstrual cycle length

The recorded menstrual cycle data from over 6,000 Clue users located in 110 countries was analyzed by researchers to determine if there was any effect on cycle length due to a COVID-19 infection or vaccination. 

The result? Researchers found a small, temporary increase in menstrual cycle length following a COVID-19 infection or vaccination. On average, unvaccinated users experiencing a COVID-19 infection reported a 1.45 day increase in their menstrual cycle length, compared to their previous average cycle length. Vaccinated users reported a similar increase in cycle length following a COVID-19 vaccination.

In both cases, users’ cycle length reverted to their previous average after one cycle.  This highlights that the impact of a COVID-19 vaccination or infection on the menstrual cycle is temporary, though noticeable. These changes are likely caused by a temporary, disease-related activation of users’ immune systems, although it’s challenging to isolate COVID-19 as the sole cause.

The reaction to the study and its findings

Alison Edelman MD, MPH, Physician-Scientist at Oregon Health & Science University, commented:

“Menstrual health is significantly understudied and underrepresented in research and medicine. This work is important and necessary to provide answers which can reassure individuals who are experiencing menstrual changes following a COVID-19 infection.”

Amanda Shea PhD, Head of Science at Clue, said:

“We are proud to contribute to such important research on the effects of COVID-19 on the menstrual cycle and to work closely with world-class researchers at Oregon Health & Science University and the University of Montpellier. This research underlines the power of Clue’s de-identified user data and its impact in advancing research into menstrual cycles and reproductive health; benefitting society via a more accurate understanding of reproductive health.”

Alexandra Alvergne PhD, CNRS scientist at the University of Montpellier, said:

“We don’t know nearly enough about infection and menstrual cycles. This study is paving the way for investigating how cycles may be affected by pathogens using unique longitudinal cycle data, a key contribution of menstrual cycle apps.”

Check out the full study here. 

How does Clue contribute to female health research?

Rooted in science, Clue was born from research and data. We continually strive to find the most accurate, forward-thinking information on menstrual and reproductive health, only sharing what we confidently believe in and can provide evidence for. From day one, we’ve been committed to closing the gender health gap by contributing to science-based studies that advance female health. 

When you track with 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.