BackgroundGlobally, there are more than 474 million cases and around 6 million deaths due to COVID-19. The case fatality rate was 0.5-2.8% while for 80-89 years old, it was 3.7-14.8%. Given the seriousness of this infection, prevention becomes critical. Hence, the introduction of vaccines led to a significant reduction (> 75% protection) in COVID-19 cases. On the other hand, patients seeking help for serious pulmonary, cardiovascular, neurological, and gynecological complaints have also been recorded. Clinical studies on the effects of vaccination focused mostly on life-or-death results rather than reproductive outcomes such as menstruation, fertility, or even pregnancy outcomes. This survey was conducted to get more evidence on the association between menstrual cycle irregularities and some globally most prevalent COVID-19 vaccines.MethodsAn online cross-sectional survey was conducted by a team from Taif University, Kingdom of Saudi Arabia, from January to June 2022 on females within the reproductive age group (15-49 years) using a semi-structured questionnaire. Data were analyzed using SPSS Statistics version 22.0 and presented as frequency and percentage. The chi-square test was applied for the association and a p-value of <0.05 was considered significant.ResultsA total of 2381 responses were included. The mean age of respondents was 25±7.7 years. Around 1604 (67%) participants observed post-vaccination menstrual changes, and the findings were significant (p< 0.001). A strong association (p=.008) was found between the type of vaccine and changes in the menstrual cycle in participants (AstraZeneca 11 (36%)) after one dose. A strong association (p=.004) was also seen between the type of vaccine (Pfizer 543 (83%)) and menstrual changes after the booster dose. Cycles became irregular 180 (36%) or prolonged 144 (29%) in females inoculated with Pfizer after two doses of vaccination (p=0.012).ConclusionPost-vaccination menstrual irregularities were reported by females of reproductive age, especially the new vaccines. Prospective studies for similar insights are needed. Finding the co-occurring impacts of vaccination and COVID-19 infections in the wake of the emerging new long-haul COVID-19 phenomena is crucial for reproductive health.