Can the COVID-19 vaccine affect women’s menstrual cycles? Here’s what we know

Women have had many questions about the COVID-19 vaccines and how it will affect their body. Some have reported changed menstrual cycles and others worry about their fertility.

ABC affiliate KGO-TV reported some women noticed changes in their menstrual cycle after getting the COVID-19 vaccine.

Hundreds commented on the report, expressing concern about long and heavy periods and changes in cycle timing.

A hematologist, someone who specializes in the study of blood and blood-forming organs and diseases, reached out to offer an explanation and advice.

“Inflammatory reaction has been noticed with the COVID vaccine,” Dr. Akshat Jain, a hematologist at Loma Linda University School of Medicine, said. “We know that because many, including myself after the second vaccine, developed some mild flu like symptoms.”

Jain specializes in bleeding disorders in young women and said that inflammatory cells triggered by the vaccine could affect hormones.

“That inflammation has a potential or potentially can modulate estrogen response, which could be the link between certain women having heavy periods after the vaccine,” Jain said.

Jain said women who are experiencing heavy bleeding should see their doctor for a complete blood count and an estrogen test.

Dr. Heather Huddleston from University of California San Francisco OBGYN said she wished vaccine makers collected data about menstrual cycles during the clinical trials.

“The train sort of left the station on that because we are now recommending the vaccine for everybody. So it will be very hard for us to generate a control group to answer this question,” Huddleston said.

She said she has been trying to think of ways to collect new data for women seeing irregular menstrual cycles such as apps.

When asked whether she thinks the vaccine is harmful to women who are experiencing cycle changes and if is affects fertility, Huddleston said, “No.”

“What I would say is that just in the same way that some women and men have had a sore arm, after the vaccine, or maybe felt tired, maybe had even a low grade fever, these are all things that people experienced in a very short-term way after the vaccine. And within a few days, people are back to normal,” Huddleston said. “That is a transient reaction to the vaccine. And it’s a representation of your immune system being activated. If, and it’s still a big if. But if these menstrual cycle changes are also sort of linked into that upregulation of the immune system that we’re seeing, then I would view that in the same way I would view a sore arm. It’s a nuisance, it’s troubling in that moment, but it’s not a representation of something that’s going to continue. It’s not a representation of any sort of permanent harm or damage. There is no reason to think there’s reason to be concerned over time, and there’s no reason to think that there’s any impact on fertility.”

Huddleston said women should continue to get the COVID-19 vaccine.

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Cox Media Group