Vaccination ultimately causes menstrual problems, according to a new French study.
- In France, many women complain of having disrupted menstrual cycles following their vaccination against Covid-19.
- A new study confirms this cause and effect relationship.
- “Compared to unvaccinated women, the risk of heavy menstrual bleeding requiring hospital treatment was increased by 20% for women whose last injection received was a primary vaccination dose administered in the previous 1 to 3 months “, summarize the authors.
Do Covid-19 vaccines have an impact on menstrual cycles? A recently published study goes in this direction, bringing new scientific elements to this controversial issue.
“As part of the enhanced surveillance system for Covid-19 vaccines, cases of menstrual disorders (delayed periods, absence of periods and abnormally heavy menstrual bleeding) have been reported, in particular on the adverse effects reporting portal” , recalls EPI-PHARE in a press release.
Covid-19: vaccination has an impact on menstrual bleeding
It is in this context that the scientific interest group carried out a new study using data from the National Health Data System (SNDS) coupled with the Covid Vaccine Information System (VAC-SI). The goal was “to measure the risk of heavy menstrual bleeding after vaccination against Covid-19 within the entire French population”, specify the authors of the report.
“The study focused exclusively on cases of heavy menstrual bleeding which received hospital treatment, because only these are identifiable from the information available in the SNDS”, they continue.
The research included 4,610 non-pregnant or postpartum women aged 15 to 50 years, with no history of hysterectomy or bleeding disorders. All had been treated in hospital for heavy menstrual bleeding between May 12, 2021 and August 31, 2022 in France. More than 70% of them were treated in day hospitals. These cases were matched to 89,375 control women with the same characteristics (age, place of residence and use of contraception).
At the time of the study, 71% of cases and 70% of controls had received at least one dose of Covid-19 vaccine. Among these vaccinated people, the last injection received was a primary vaccination dose (first or second dose) for 68% and 66%. The last vaccine received was mRNA (Comirnaty or Spikevax) for 99.8% of the cohort.
Vaccination against Covid-19: no heavy menstrual bleeding after a booster dose
Compared to unvaccinated women, the risk of heavy menstrual bleeding requiring hospital treatment was increased by 20% for women whose last injection received was a primary vaccination dose administered within the previous 1 to 3 months. On the other hand, this risk was not increased for women whose last injection received was a primary vaccination dose more than 3 months old or a booster dose.
Assuming a causal relationship, the estimated number of cases of heavy menstrual bleeding requiring hospital treatment attributable to primary vaccination between May 12, 2021 and August 31, 2022 in France was 103, i.e. a rate of 8 cases per 1,000,000 vaccinated women across all 13 million French women aged 15 to 50 vaccinated as of August 31, 2022.
“These results provide new arguments in favor of the existence of an increased risk of heavy menstrual bleeding in the 3 months following primary vaccination against Covid-19 with an mRNA vaccine,” summarize the members of EPI-PHARE. “On the other hand, the results do not indicate an increased risk of heavy menstrual bleeding after a booster dose,” they conclude.
In May 2023, a study published in the British Medical Journal indicated that there was no “solid basis for a causal link between vaccination against SARS-CoV-2 and consulting for a menstrual disorder or bleeding.
