In a recent survey, 42% of women said they experienced heavier menstrual bleeding following SARS-CoV-2 vaccination.
Results also showed that a majority of non-menstruating, premenopausal women taking hormonal treatments experienced breakthrough bleeding after vaccination.
Researchers said this possible side effect was likely missed in clinical trials, which did not assess menstrual cycles or bleeding. Analyses of the survey data, which were published in Science Advances, revealed certain characteristics were associated with changes in menstruation.
“This is the very first characterization