Prevalence of menstrual alterations following COVID-19 vaccination: systematic review & meta-analysis

COVID-19 vaccines can lead to diverse local and systemic side effects, but there is limited evidence concerning their association with menstrual cycle changes. This study aimed to assess the prevalence of menstrual cycle alterations after COVID-19 vaccination among adult women.

We systematically searched the PubMed, Web of Science and Science Direct databases for observational studies that included adult women and investigated the range of menstrual alterations. The quality of the studies was evaluated via the Newcastle-Ottawa scale. All the data were analyzed via Comprehensive Meta-Analysis Software Version 4.0. Forest plots were created to calculate the individual and pooled prevalence rates of different types of menstrual changes and 95% confidence intervals (CI) via fixed-effects and random-effects models, as appropriate. Heterogeneity was assessed with Q statistics and the I² test.

Eleven studies, encompassing 26,283 adult women, met our eligibility criteria. Among the selected studies, five were cohort studies, five were cross-sectional studies, and one employed a case‒control design. The menstrual changes included abnormal cycle duration, dysmenorrhea, irregular cycles, and abnormal cycle flow (heavy and light flow), with pooled percentages of 27.3% (CI: 7.2-64.6%), 22% (CI: 5.2-59.4%), 16% (CI: 5.8-37.2%), 11.7% (CI: 5.8-22%), and 5.5% (CI: 2.3-12.5%), respectively.

This review highlights the prevalence of menstrual changes after COVID-19 vaccination and emphasizes the importance of considering menstrual health as an integral part of postvaccination monitoring and health care interventions. However, longitudinal studies are essential for establishing a definitive causal relationship between COVID-19 vaccination and menstrual alterations.