Results from recent research studies show that people who menstruate may observe small, temporary changes in menstruation after COVID-19 vaccination, including:
- Longer duration of menstrual periods
- Shorter intervals between periods
- Heavier bleeding than usual
Despite these temporary changes in menstruation, there is no evidence that COVID-19 vaccines cause fertility problems. A study of more than 2,000 women ages 21-45 years and their partners found that COVID-19 vaccination of either partner did not affect the likelihood of becoming pregnant. COVID-19 vaccination is recommended for people who are trying to get pregnant now or might become pregnant in the future, as well as their partners. Learn more about COVID-19 vaccination for people who would like to have a baby.
Menstrual cycle changes are normal throughout the course of the year, and could be caused by stress, fatigue, or other lifestyle changes. If menstrual cycle changes persist, talk to your healthcare provider. You can also make a report using the V-safe After Vaccination Health Checker tool on your smartphone vsafe.cdc.gov. Harmful side effects can be reported through the Vaccine Adverse Event Reporting System (VAERS): https://vaers.hhs.gov/esub/index.jsp.