Effects of Covid-19 Vaccines on the Menstrual Cycle: A Cross-Sectional Study

Background: Prior clinical studies that sought to investigate the safety and efficacy of Covid-19 vaccines did not list menstrual cycle changes as a side-effect. However, following reported cases of menstrual cycle disturbances after vaccination, this study sought to examine the link between Covid-19 vaccination and post-vaccine menstrual cycle abnormalities in pre- and post-menopausal women. Methods: A cross-sectional research design approach using online surveys was employed to investigate the link between vaccination and changes in menstrual cycle. The participants consisted of a cohort of 657 pre- and post-menopausal women with the majority drawn from the reproductive age group (25-44 years). The inclusion criteria was that participants must have received any type of Covid-19 vaccine, not be pregnant and those that did not have a negative diagnosis in any gynecologic condition. Of the eligible sample size, only 344 participants met the inclusion criteria. The sociodemographic and menstrual cycle data was collected from an online survey. Data was analyzed using descriptive, inferential chi-square tests, logistic regression, and correlation. Results: The results partially confirmed the findings from prior studies that Covid-19 vaccination is associated with significant changes in the women’s menstrual cycle flow and menstrual period length even after controlling for age, Body Mass Index, and ethnicity. Other menstrual cycle disturbances such as missed periods, cycle regularity, and spotting/vaginal bleeding were noted to be less significant. However, the extent of menstrual cycle changes was less severe and decreased after the second dose vaccination. It was found that 11.1% and 37.5% of post-menopausal women reported menstrual symptoms after the first and the second dose cycle respectively. Conclusion: The study concludes that although Covid-19 vaccines tend to adversely affect women’s menstrual cycle, these changes are short-lived. The findings have important implications in enhancing the success of Covid-19 vaccination programs by reducing cases of vaccine hesitancy among reproductive-age women