Study Shows COVID-19 Vaccination Can Temporarily Change Menstrual Cycles

A new study shows COVID-19 vaccines may temporarily change a woman’s menstrual cycle. 

A new study that’s now been published in the British Medical Journal shows there’s a connection between vaccinated women having longer periods as a result of the COVID-19 vaccination. The study consisted of 20,000 participants who recorded their data via the Natural Cycles app and tracked their cycles from October 1, 2020, to November 7, 2021, KCRA reports. The participants were broken up into two groups: vaccinated and unvaccinated. 

Almost 10,000 vaccinated participants received the Pfizer/BioNTech vaccine; others had a vaccination from Johnson & Johnson and Moderna. Those who received a double dose vaccine were shown to have had a longer cycle of more than three days compared to those who weren’t vaccinated. There were no changes in the length of time that a woman bled. 

All of the side effects are still being analyzed. “I think that we probably need to look into it a lot more and just kind of get more of these individual accounts and get a little bit more of this information before we can make kind of these generalizations about what the effects potentially could be,” said UC Davis obstetrics and gynecologist Nandini Nittur, KCRA reports.