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New studies investigate whether COVID-19 vaccines linked to menstruation side effects

NIH awarded $1.67 million to five institutions to explore a potential impacts of COVID-19 vaccination on menstruation

BALTIMORE — Women have reported changes to their monthly menstrual cycles as a result of the COVID-19 vaccines. Now, the National Institutes of Health are launching a study to explore whether there is a possible connection.

Health officials have said in the past that there is no data linking the vaccines to changes in menstruation, but NIH said some women have reported experiencing irregular or missing menstrual periods, bleeding that is heavier than usual, and other menstrual changes after receiving COVID-19 vaccines.

NIH awarded $1.67 million to five institutions to support research to determine whether such changes may be linked to COVID-19 vaccination itself and how long the changes last. Researchers will also seek to clarify the mechanisms underlying potential vaccine-related menstrual changes, NIH said in a release

One of the institutions is Johns Hopkins School of Medicine's Department of Gynecology and Obstetrics in Baltimore, Md.

“There may be several reasons why a woman might experience unscheduled menstrual bleeding, abnormal periods or bleeding that is heavier than usual,” said lead investigator Mostafa Borahay, M.D., Ph.D., associate professor of gynecology and obstetrics at the Johns Hopkins University School of Medicine. “This research will help us better understand if there’s a real link between the COVID-19 vaccines and these menstrual changes, or if it’s something else, such as lifestyle changes or pandemic-related stress.”

Borahay and his team hypothesize that the immune response following vaccination may bring immune cells into the endometrium (uterus). This may result in the menstrual irregularities that women are reporting, the researchers said. 

RELATED: VERIFY: What's behind menstruation changes after the COVID-19 shot?

“If there’s a relationship between the COVID-19 vaccines and the menstrual changes, we need to know how it happens,” Borahay said in a release. “Therefore, we plan to examine the response of the endometrium to the COVID-19 vaccination at the biological level.”

RELATED: VERIFY: No link between coronavirus vaccines and fertility

Additional studies will be conducted at Boston University, Harvard Medical School, Michigan State University and Oregon Health and Science University.

The new projects will build on existing research studies and leverage data from menstrual tracking apps to evaluate the potential impacts of COVID-19 vaccination on menstrual health among geographically and racially and ethnically diverse populations. One project will focus specifically on adolescents, NIH said.

“These rigorous scientific studies will improve our understanding of the potential effects of COVID-19 vaccines on menstruation, giving people who menstruate more information about what to expect after vaccination and potentially reducing vaccine hesitancy,” said NICHD Director Diana W. Bianchi, M.D.

RELATED: CDC issues advisory urging pregnant people to get COVID vaccine

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