Effect of COVID-19 vaccinations on menstrual cycle and postmenopausal bleeding among health care workers: A cross-sectional study.

Objective: To determine the effect of coronavirus disease 2019 (COVID-19) vaccination and its association with sociodemographic factors on the menstrual cycle in premenopausal women and on postmenopausal bleeding.

Methods: This is a retrospective cross-sectional study conducted between September 22, 2022, and November 30, 2022, via a questionnaire distributed to 359 health care workers (HCWs) at Lebanese American University Medical Center-Rizk Hospital and St John's Hospital. Inclusion criteria included female Lebanese HCWs who were vaccinated and aged 18 to 65 years.

Results: Change in cycle length was significantly associated with age (P = 0.025 after the first dose and P = 0.017 after the second dose), level of education (P = 0.013 after the first dose and P = 0.012 after the second dose), and fibroids (P = 0.006 after the second dose and P = 0.003 after the third dose). The change in cycle flow was significantly associated with age (P = 0.028), fibroids (P = 0.002 after the second dose and P = 0.002 after the third dose), bleeding disorders (P = 0.000), and chronic medications (P = 0.007). The change in symptoms was associated with polycystic ovary syndrome (P = 0.021), chronic medications (P = 0.019 after the second dose and P = 0.045 after the third dose), and fibroids (P = 0.000).

Conclusion: COVID-19 vaccination can influence the menstrual cycle. Age, body mass index, level of education, underlying comorbidities, and use of chronic medications are significantly associated with changes in menstrual length, flow, and symptoms following vaccination.