Having COVID-19 was linked to a slight, temporary change in menstrual cycle length similar to changes seen after COVID-19 vaccination, according to a study of self-reported data from a menstrual tracking app. People who experienced COVID-19 had a 1.45-day adjusted increase in cycle length during COVID-19 infection compared with the three cycles before infection (95% CI 0.86-2.04), while those who were vaccinated against COVID-19 had a 1.14-day adjusted increase in cycle length after being vaccinated compared to previous cycles (95% CI 0.60-1.69).
Although both those changes were more than the 0.68-day decrease in cycle length seen in the control group of people who were neither vaccinated nor reported to have COVID-19, the vaccinated and infected groups did not differ significantly from each other.
And for both groups, the cycle changes disappeared by the next cycle, reported Alexandra Alvergne, PhD, of the Institute for Evolutionary Sciences at Montpellier University in France, and co-authors published in Obstetrics & Gynecology “The change in cycle length was minimal and limited to only the cycle of either illness or vaccination,” commented Pamela Berens, MD, an ob/gyn at the McGovern Medical School at UTHealth Houston, who was not involved in the study. “[This research] might provide some reassurance to patients who are concerned about the impact of COVID-19 or vaccination on their cycles.”