Menstrual cycle disturbances after COVID-19 vaccination

Introduction: After COVID-19 vaccination, women of reproductive age reported changes in their menstrual cycle. Materials and methods: A retrospective study was carried out after a survey on social networks that included women aged 18-41 years with normal cycles according to International Federation of Gynecology and Obstetrics and who were vaccinated (complete schedule for two doses, except J&J/Janssen or incomplete with a single dose). Women with following conditions were excluded: pregnant or lactating women; history of diseases that cause menstrual irregularities or early menopause: anorexia, bulimia, polycystic ovary syndrome, hypothyroidism, obesity, or low weight; hysterectomized or oophorectomized patients; and high performance athletes. Results: Overall, 950 women completed the survey between July and September 2021. In total, 408 women met the inclusion criteria, and 184 reported the following characteristics: frequency (normal 43.47%, infrequent 25%, and frequent 31.53%), regularity (regular 51.08%, irregular 42.93%, and absent/amenorrhea 5.97%), duration (normal 65.21%, prolonged 26.08%, absent/amenorrhea 8.69%), and volume (heavy 41.84%, light 20.65%, and absent/amenorrhea 6.52%). Conclusions: SARS-CoV-2 infection and COVID-19 vaccination can influence the menstrual cycle and cause alterations.