What Do We Know About Abnormal Uterine Bleeding Following Vaccination Against Covid-19 After Two and A Half Years Of Experience? A Systematic Review and Meta- Analysis

Abstract

Vaccination against COVID-19 is regarded to be most effective in preventing morbidity and mortality and limiting the spread of the virus. Publications in the media and scientific journals have raised a concern regarding abnormal uterine bleeding as a COVID-19 vaccine side effect. We aimed to estimate the prevalence of abnormal uterine bleeding after vaccination against COVID-19. Medline, PubMed, Embase and Google Scholar databases were searched between January 2020 and June 2022. English-language studies, including at least four women with abnormal uterine bleeding. Eligible studies were assessed for risk of bias using the Newcastle-Ottawa Scale. Data synthesis was accomplished by meta-analysis of frequencies of the abnormal uterine bleeding rate and meta-regression of the rate adjusted for the type of vaccine and number of vaccinations. There were 12 eligible studies including a total of 1,132,613 women of whom 41,344 (31.3%, 95CI 11.7-55.1%) reported abnormal bleeding following vaccination. Nine studies included clinical presentation: the abnormality was menorrhagia in 38%, irregular menses in 28%, intermenstrual bleeding in 12% and delayed menses in 9%). There was considerable heterogeneity in results which could not be accounted for by the method of recording abnormal bleeding, vaccine manufacturer or number of doses. COVID-19 vaccine carries the inconvenience of abnormal uterine bleeding in almost one-third of the women vaccinated, mostly irregular menses or menorrhagia. In addition, the innovative vaccine mechanism could be used against various potential targets, further highlighting the need to assess vaccine side effects.