By Dr. Max Gomez

NEW YORK (CBSNewYork) — Thousands of women are reporting a potential side effect of the COVID vaccine when it comes to their monthly menstrual cycles.

Top federal researchers are now launching a study to see if there is a possible connection, CBS2’s Dr. Max Gomez reported Monday.

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When Dr. Katharine Lee from Washington University got her COVID vaccine, she experienced something unexpected.

“I ended up with really strong cramps and a little bit of breakthrough bleeding after both vaccines,” Lee said.

After a friend and fellow scientist had similar changes after the shot, they created a survey that has received more than 150,000 responses describing excessive or more frequent bleeding, more pain and missed periods.

“The information that we have is anecdotal,” said Dr. Diana Bianchi, director at the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

Even so, the National Institutes of Health has launched a new study to investigate if there’s a connection between COVID-19 vaccination and monthly cycles.

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Dr. Bianchi is leading the research.

“I can’t stress enough the importance of having a control group to be able to dissect out whether it is actually the vaccines causing the changes,” Bianchi said.

The research may also provide clear information for women concerned about the short and long term effects of the vaccine on reproductive health.

“I believe that there’s a certain percentage of people who are hesitant because they don’t have enough information, and that’s our goal, is to provide information and reassure people that whatever changes occur with the menstrual cycle are temporary and that they do not affect your fertility,” said Bianchi.

COVID is really bad. It makes people very sick, and having a couple of months of cramping or spotting, for me personally, is totally worth the protection,” Lee said.

Researches in the U.K. are also planning to study the possible connection after almost 30,000 reports of monthly changes.

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All of the researchers stress that the menstrual changes are temporary and that all of the studies looking at fertility have found the COVID vaccines do not impair your chances of having a baby.

Dr. Max Gomez