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Updated: Aug 16, 2025
Collection, Isolation, and Flow Cytometric Analysis of Human Endocervical Samples
Published on: July 6, 2014
COVID-19 vaccination and changes in the menstrual cycle among vaccinated persons
Leslie V Farland1, Sana M Khan2, Alexandra Shilen2
1Department of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health, University of Arizona; Department of Obstetrics and Gynecology, College of Medicine-Tucson, University of Arizona; University of Arizona Cancer Center, University of Arizona.
Objective:
To describe the characteristics of people who experience changes to their menstrual cycle after COVID-19 vaccination.
Design:
Longitudinal study.
Patient(S):
We recruited a volunteer sample with and without a history of SARS-CoV-2 infection who enrolled in the Arizona COVID-19 Cohort (CoVHORT) study and participated in a reproductive sub-cohort who were pre-menopausal, not pregnant, and had received a COVID-19 vaccine in 2021 (n = 545).
Exposure(S):
Demographic and reproductive characteristics were collected via self-reports.
Main Outcome Measure(S):
Information on self-reported changes in the menstrual cycle after COVID-19 vaccination was collected from May 2021 to December 2021. We looked at demographic and reproductive characteristics as predictors of menstrual cycle change.
Result(S):
The majority of our vaccinated sample received the Pfizer-BioNTech vaccine (58%), and were 26-35 years old (51%), non-Hispanic (84%), and White (88%). Approximately 25% of vaccinated participants reported a change in their menstrual cycle after vaccination; the majority reported changes after their second dose (56%) as compared with their first (18%) and third (14%) doses. The most commonly reported changes were irregular menstruation (43%), increased premenstrual symptoms (34%), increased menstrual pain or cramps (30%), and abnormally heavy or prolonged bleeding (31%). High self-reported perceived stress levels compared with low perceived stress (OR, 2.22; 95% CI 1.12-4.37) and greater body mass index (OR, 1.04; 95% CI 1.00-1.07) were associated with greater odds of experiencing the menstrual cycle changes after the vaccination. Participants having a history of SARS-CoV-2 infection were less likely to report changes in their menstrual cycle after vaccination compared with the participants with no history of SARS-CoV-2 infection (OR, 0.58; 95% CI 0.32-1.04).
Conclusion(S):
Among vaccinated participants, approximately 25% of them reported predominantly temporary changes in the menstrual cycle, however, we are unable to determine whether these changes are due to normal cycle variability. The COVID-19 vaccines are safe and effective for everyone, including pregnant people and people trying to conceive; hence, these findings should not discourage vaccination.
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