Understanding how the COVID-19 vaccine affects your body and what to expect is important.
On social media, many women have shared anecdotes about how the vaccine has affected their periods. Individuals reported heavier periods, earlier cycles and more painful cramps after receiving the vaccine. These reports have caused vaccine hesitancy among some.
But a new study published in the peer-reviewed journal Obstetrics & Gynecology found that while pandemic-related stress can cause changes in period cycles, the vaccine itself does not cause drastic side effects to cycle length.
Until now, there have not been any clinical studies that record the potential side-effects of the vaccine on periods, and evidence has been mainly anecdotal. Researchers tracked menstrual cycles using data collected from the fertility app, Natural Cycles.
The study followed 3,959 individuals, of whom 2,403 were vaccinated and 1,556 were unvaccinated. Researchers tracked six cycles for both groups. The study followed three cycles before vaccinated individuals received their doses and three cycles after their vaccine.
The results showed that there were only small, temporary changes in cycle length. On average, there was a 0.71 increase in cycle length after the first dose and a 0.91 increase in cycle length after the second dose. Additionally, there were no reported changes in days of menses — days of bleeding. These changes were temporary and usually lasted for one to two cycles, according to the study.
“It is reassuring that the study found only a small, temporary menstrual change in women,” said Diana W. Bianchi, M.D., director of NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, in a news release. “These results provide, for the first time, an opportunity to counsel women about what to expect from COVID-19 vaccination so they can plan accordingly.
The changes you may experience to your period after receiving the vaccine are mild and temporary, and this change is not harmful to your health.
Short-term changes to your period after receiving the vaccine do not affect fertility and the chances of becoming pregnant. Furthermore, the Centers for Disease Control and Prevention recommends pregnant and lactating individuals get vaccinated.
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