Impact of coronavirus disease 2019 (COVID-19) vaccination on menstrual bleeding quantity: an observational cohort study
Author(s)
Type
Journal Article
Abstract
OBJECTIVE: To assess whether coronavirus disease 2019 (COVID-19) vaccination impacts menstrual bleeding quantity. DESIGN: Retrospective cohort. SETTING: Five global regions. POPULATION: Vaccinated and unvaccinated individuals with regular menstrual cycles using the digital fertility-awareness application Natural Cycles°. METHODS: We used prospectively collected menstrual cycle data, multivariable longitudinal Poisson generalised estimating equation (GEE) models and multivariable multinomial logistic regression models to calculate the adjusted difference between vaccination groups. All regression models were adjusted for confounding factors. MAIN OUTCOME MEASURES: The mean number of heavy bleeding days (fewer, no change or more) and changes in bleeding quantity (less, no change or more) at three time points (first dose, second dose and post-exposure menses). RESULTS: We included 9555 individuals (7401 vaccinated and 2154 unvaccinated). About two-thirds of individuals reported no change in the number of heavy bleeding days, regardless of vaccination status. After adjusting for confounding factors, there were no significant differences in the number of heavy bleeding days by vaccination status. A larger proportion of vaccinated individuals experienced an increase in total bleeding quantity (34.5% unvaccinated, 38.4% vaccinated; adjusted difference 4.0%, 99.2% CI 0.7%-7.2%). This translates to an estimated 40 additional people per 1000 individuals with normal menstrual cycles who experience a greater total bleeding quantity following the first vaccine dose' suffice. Differences resolved in the cycle post-exposure. CONCLUSIONS: A small increase in the probability of greater total bleeding quantity occurred following the first COVID-19 vaccine dose, which resolved in the cycle after the post-vaccination cycle. The total number of heavy bleeding days did not differ by vaccination status. Our findings can reassure the public that any changes are small and transient.
Date Issued
2023-06
Date Acceptance
2023-03-06
ISSN
1470-0328
Publisher
Wiley
Start Page
803
End Page
812
Journal / Book Title
BJOG: an International Journal of Obstetrics and Gynaecology
Volume
130
Issue
7
Copyright Statement
© 2023 The Authors. BJOG: An International Journal of Obstetrics and Gynaecology published by John Wiley & Sons Ltd.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Identifier
https://obgyn.onlinelibrary.wiley.com/doi/10.1111/1471-0528.17471
https://www.ncbi.nlm.nih.gov/pubmed/37035899
Subjects
COVID-19 vaccination
bleeding quantity
menstrual cycle
menstruation
bleeding quantity
COVID-19 vaccination
menstrual cycle
menstruation
11 Medical and Health Sciences
Obstetrics & Reproductive Medicine
Publication Status
Published
Coverage Spatial
England
Date Publish Online
2023-04-10