No, it’s not just you: The COVID-19 vaccine is indeed linked to changes in your menstrual cycle, according to a new study funded by the National Institutes of Health (NIH).
For the study, researchers analyzed period-tracking data from nearly 20,000 cisgender women across the United States, the United Kingdom, Canada, and Europe to explore any changes to the length of their cycles after receiving the COVID-19 vaccine. About 15,000 participants were vaccinated; roughly 5,000 were not. Researchers looked at four menstrual cycles per participant. For vaccinated people, they studied three cycles prior to inoculation and one after.
On average, vaccinated participants reported bleeding for an additional .71 days after their first vaccine dose and .56 days after their second. Younger women and women who had longer cycle length before getting vaccinated were more likely to experience this increase.
It’s worth noting that these reported changes were temporary and all within the “normal range of variation” for menstrual cycles, which is eight days. As such, there do not appear to be any dramatic or lasting effects on women’s reproductive health linked to the vaccine.
“These findings provide additional information for counseling women on what to expect after vaccination,” said Diana Bianchi, M.D., director of NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, in a statement. “Changes following vaccination appear to be small, within the normal range of variation, and temporary.”
The new study builds upon an existing body of research about how the COVID-19 vaccine impacts women’s health, including a similar report from January. It also corroborates months of anecdotal reports from women around the world.
The CDC recommends the COVID-19 vaccine for all people ages 6 and older, including people who are breastfeeding or pregnant and people who may become pregnant in the future. Those who are fully vaccinated are at lower risk of severe illness, hospitalization, or death from COVID-19. As the pandemic stretches on, consider getting vaccinated or boosted to keep yourself, your loved ones, and your community safe.
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