Menstrual Cycle Changes after the COVID-19 Vaccine: A Cross-sectional Study in Saudi Arabia

Abstract

Various side effects of the COVID-19 vaccine, such as fatigue, have been reported. However, there has been a recent increase in reports of menstrual cycle changes among women. This study assessed the effect of the COVID-19 vaccine on the menstrual cycle of Saudi women. In this cross-sectional study, data were collected between November and December 2021 from 500 healthy Saudi females between 20 and 40 years. We included all women who reported having a normal menstrual cycle before being vaccinated against COVID-19. A total of 65.6% of participants reported having significant changes in their cycle in terms of period timing, blood flow, and pain following the first and 65.6.% following the second COVID-19 vaccination doses. Both the mRNA and adenovirus vectored COVID-19 vaccines affected the cycle similarly. The induced COVID-19 vaccine menstrual cycle abnormality is a short-term effect lasting <3 months after the first and second doses. There are reported side effects of the COVID-19 vaccine; however, changes in the menstrual cycle have not been reported. Our study assumes that the menstrual cycle changes observed in the study’s participants were unlikely to be caused by reasons other than the COVID-19 vaccines, since we excluded all participants with medical interventions, medical conditions, and the age range that might affect the menstrual cycle. Although this effect is a short-term effect, the exact mechanism behind this phenomenon must be investigated.