An American study reported on changes in cycle or menses length in women receiving COVID-19 vaccination and concluded that COVID-19 vaccination is associated with a small change in cycle length but not menses length.

A total of 3,959 individuals (2,403 vaccinated and 1,556 unvaccinated women) were included in the study. Overall, COVID-19 vaccine was associated with a less than one day change in cycle length for both vaccine-dose cycles compared with pre-vaccine cycles. No significant changes were noted in menses length with vaccination.

individuals who received both vaccine doses in a single cycle had, on average, a two day increase in their vaccination cycle length compared with unvaccinated individuals. Although approximately 10% of the latter group experienced a clinically notable change in cycle length of 8 days or more, this change quickly resolved with a return to normal cycle pattern within two post-vaccine cycles.

These are reassuring findings and provide useful information when counselling women. Please click here to access the report.