COVID vaccine linked to small & temporary increase in menstrual cycle length, says study
January 14, 2022 13:43 ISTMost vaccinated users received the Pfizer and Moderna vaccines. On average, the first vaccination dose was associated with a .71-day cycle increase in cycle length and the second dose with a .91-day increase. Therefore, users vaccinated over two cycles had an increase of less than one day in each of the vaccination cycles.