A survey conducted in United Kingdom women in March of 2021 found no concerning changes in menstrual periods among women who received the COVID-19 vaccines, UK researchers reported yesterday in the journal iScience.
For the study, the team asked women about menstrual changes during the pandemic, their COVID-19 vaccination history, and whether they had been sick with the virus. The participants included nearly 5,000 premenopausal women who had been vaccinated. Researchers found that 82% reported no changes. Of the 18% who reported changes, risks were higher in people who smoked, had previously been sick with COVID-19, or were not using oral contraceptives.
When the investigators looked at a wider group of 12,000 participants, which included unvaccinated women, they found no greater risk of disruption in vaccinated women than their unvaccinated peers who had never been sick with the virus. However, those with a history of COVID-19 were more likely to report heavy bleeding, missed periods, and bleeding between periods.
Jackie Maybin, MBChB, PhD, a study author with the University of Edinburg's MRC Centre for Reproductive Health, said in a University of Edinburgh press release that the results may reflect some bias, due to those who chose to complete the survey. "Nevertheless, our results are reassuring that Covid-19 vaccination does not cause concerning menstrual changes, and helpful for identifying people who might be at higher risk of experiencing menstrual disturbance."