Many women have reported noticing changes in their menstrual cycle after being vaccinated against Covid-19 but a new study of 1,273 women in the UK found no correlation, according to a report posted on Monday on medRxiv ahead of peer review. The women in the study kept careful records of their cycles and their vaccination dates. "We were unable to detect strong signals to support the idea" that Covid-19 vaccines are linked to changes in timing or flow of women's periods, said Victoria Male from Imperial College London.
It is possible that larger studies, or studies in other countries, might find links, she said. "It is important to note that most people who report such a change following vaccination find that their period returns to normal the following cycle." Other studies have found no evidence that the vaccines affect female fertility, Male added.