There is growing public concern that COVID-19 vaccination causes menstrual cycle disorders, with respect to the relative effect of vaccination versus SARS-CoV-2 infection. Our objectives were to test potential risk factors for menstrual cycle alteration after COVID-19 vaccination and to compare male endpoints after COVID-19 vaccination and COVID-19 disease. We performed a secondary analysis of a retrospective online survey conducted in the United Kingdom in March 2021. Among premenopausal vaccinated participants (n = 4,989), 18% reported menstrual cycle changes after their first COVID-19 vaccine injection. The prevalence of menstrual changes was higher among women who smoked, had a history of COVID-19 vaccine-related illness, or were not using estradiol-containing contraceptives. In a second sample that included both vaccinated and unvaccinated participants (n = 12,579), COVID-19 vaccination alone was not associated with abnormal menstrual cycle parameters, whereas a history of COVID-19 disease was associated with an increased risk of reporting heavier bleeding, "missed" periods, and intermenstrual bleeding.
I'm interested in women's reproductive health through the prism of ecology...More