The effect of BNT162b2 SARS-CoV-2 mRNA vaccine on menstrual cycle symptoms in healthy women
Abstract
Objective: To investigate the impact of the SARS-CoV-2 mRNA BNT162b2 vaccine on women's menstural cycle.
Methods: In this questionnaire-based cross-sectional study, we assessed menstrual pattern and changes of women who completed the SARS-CoV-2 mRNA BNT162b2 vaccine three months before and after receiving the vaccine. Included were women aged 18-50 without known gynecological comorbidities who regularly monitor their menstruation through electronic calendars. All participants competed a detailed questionnaire on their menstrual symptoms including information on any irregular bleeding. To minimize bias, each woman served as a self-control before and after vaccination. Primary outcome was rate of irregular bleeding following vaccination and secondary outcome was presence of any menstrual change, including irregular bleeding, mood changes or dysmenorrhea following the vaccine.
Results: A total of 219 women met the inclusion critieria. Of them, 23.3% (n=51) experienced irregular bleeding following the vaccine. Almost 40% (n=83) of study participants reported any menstrual change following vaccination. Parity was positively associated with irregular bleeding with 50% (n=26) of those suffering from irregular bleeding being multiparous as compared to only 31.5% (n=53) of women with no irregular bleeding (nulliparous 46% vs 60%, multiparous 50% vs 31%, rest 4% vs 8%, p=0.049). The presence of medical comorbidities was also significantly higher among patients who experienced irregular bleeding (20.0% vs 6.0%, p=0.003).
Conclusion: Our study shows relatively high rates of irregular bleeding and menstrual changes after receiving the SARS-CoV-2 mRNA BNT162b2 vaccine. Further research is needed to confirm our findings and to better characterize the magnitude of change and any possible long term implications.