ABSTRACT
Objective: To evaluate ifthe COVID-19vaccine produces changes in the menstrual pattern, type ofchange anddysmenorrhea. Methods: Observational and cross-sectional study. 6616 digital surveys were carried out on women who received a vaccine against COVID-19. Asurvey was applied via networks and in gynecological consultations. Percentages and 95 %confidence intervals were calculated from 2x2 tables, menstrual changes were analyzed in the sample and in subgroups according to type of vaccine, number of doses, age, and residence. Results: 86.5 % (3535/4087) reported menstrual changes, the most frequent being: menstrual delay (40.4 %) and heavier menstrual bleeding (37.7 %). Dysmenorrhea presented in 39 % accompanying menstrual changes, but 2.1 % as the only symptom. A statistically significant difference was observed: 1) more menstrual changes with mechanism of action chimpanzee viral vector when compared to inactivated virus, 2) human viral vector and inactivated virus more menstrual changes 18-34 years compared to 35-50 years and less changes when compared to chimpanzee viral vector in 35-50 years 3) mRNA was the least associated with menstrual absence when compared to human viral vector 53 % and chimpanzee 50 % more frequent. Conclusion: Menstrual changes are very common after vaccination against COVID-19, this being related to the type of vaccine administered. Some mechanisms of action seem to be related to a greater or lesser risk of specific menstrual changes. © 2023 Sociedad de Obstetricia y Ginecologia de Venezuela. All rights reserved.