FACT BRIEF

Can the COVID-19 vaccine affect women’s menstrual cycles?

Friday, April 1, 2022

By Lisa Freedland

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YES

Analyzing data from nearly 4,000 women between the ages of 18 and 45, a study collecting data through a menstrual cycle tracking app found that women vaccinated with the COVID-19 vaccine experienced a slight, temporary increase in the time between their menstrual cycles.

Researchers discovered that on average, women who received their first COVID-19 vaccine saw a temporary cycle length increase of 0.71 days, while women who received their second during the study saw a 0.91-day increase. Researchers noted, "The increase in cycle length for both the first and second vaccine cycles appears to be driven largely by the 358 individuals who received both vaccine doses within a single [menstrual] cycle."

Menses, or days of bleeding, did not increase in the vaccinated group relative to the unvaccinated group.

Scientists caution that menstrual cycle changes of less than eight days are normal and encourage women to continue receiving the COVID-19 vaccine.

This fact brief is responsive to conversations such as this one.

Sources

Lippincott Research Association Between Menstrual Cycle Length and Coronavirus D... : Obstetrics & Gynecology

National Institutes of Health COVID-19 vaccines linked to small increase in menstrual cycle length

Hackensack Meridian Health What You Should Know About COVID Vaccines & Menstrual Cycles

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