A recent international study published in the British Journal of Obstetrics and Gynaecology suggests that women vaccinated for COVID-19 may have a slightly increased risk of experiencing heavier periods following vaccination. Researchers from Oregon Health & Science University analyzed data from 9,555 individuals, predominantly from the US, Canada, the UK, and Europe. They found a 4% increase in total bleeding quantity after the first vaccine dose, amounting to approximately 40 more individuals per 1,000 experiencing increased bleeding. These changes, however, typically resolved by the first menstrual cycle after vaccination.
This study builds upon previous findings regarding menstrual cycle alterations post-vaccination and emphasizes the importance of understanding these changes to reassure the public. Lead researchers Blair Darney and Alison Edelman aim to validate individual experiences while encouraging those with prolonged menstrual irregularities to consult healthcare professionals. Although the study did not investigate the biological mechanisms behind these changes, the researchers note that immune responses to vaccination may play a role. Future research will explore the impact of COVID-19 infection on menstrual cycles, in addition to vaccine-related changes.
