In June 2021, a team of researchers gathered data from 39,129 women, all of whom received two doses of the coronavirus vaccine at least two weeks before the study was conducted. The group received vaccines from Pfizer, Moderna, AstraZeneca, Johnson & Johnson, Novavax, and other pharmaceutical companies. Dr. Kathryn Clancy is a professor of anthropology at the University of Illinois Urbana-Champaign, and she conducted the research alongside Dr. Katherine Lee, a professor of anthropology at Tulane University.
Covid Vaccine Caused 42% of Women To Experience a Disrupted Menstrual Cycle in a Study of over 39,000 People
“Dr. Lee and I had our own wonky period experiences post-vaccine,” Dr. Clancy said. “If Dr. Lee hadn’t pointed them out to me first, I may never have made the connection myself."
"After I tweeted about it and the response was overwhelming, we designed a survey instrument that would allow us to capture these experiences as well as any factors that might make one more at risk of this side effect. We really wanted to listen to people and validate their concerns because there were so many who were quick to dismiss them.”
They only gathered research from women over the age of 18 who were experiencing menstrual cycles regularly and excluded perimenopausal women.
The data showed that 42.1% of women had a heavier menstrual flow after they were vaccinated, and many said that this happened within the first seven days of getting the jab. Others noted that they saw these menstrual changes 8-14 days after the vaccine.
“Our key finding is that increased bleeding (heavier among menstruating people, and breakthrough bleeding among non-menstruating people) is real, mechanistically plausible and experienced by a significant number of people,” Dr. Clancy said. “It is also now supported by several prospective studies that have also found the same thing.”
“A secondary finding is that there are key factors that increase the chance someone may have this increased bleeding phenotype – being older (for menstruating people – younger if postmenopausal), having been pregnant/had kids, having a hyperproliferative reproductive condition.”
Dr. Clancy also explained that the uterus is "an immune organ," and when the immune system is activated by a vaccine there are "all sorts of downstream effects, including on the uterus." A disruption of immune function can easily cause disruptions in the way the lining of the uterus bleeds and clots.
The authors of this study insist that this data only points to the need for more clinical trials about how the coronavirus vaccine affects women's menstrual cycles.
“At minimum, trials should include questions about menstrual periods and the daily adverse reporting should extend to at least 14 days because many of our respondents got their heavy periods outside of the 7-day window common in most trial designs,” Dr. Clancy said. “We had some participants tell us that they were involved in vaccine trials and that they tried to report their symptoms – in one case the person they talked to dismissed their concerns and said ‘you just must be perimenopausal’ rather than writing down their symptoms.”
After all this time, the women who were gaslit about their menstrual cycles being disrupted by the vaccine can rest easy knowing that they're certainly not the only ones.