It is very difficult to establish a link between anti-COVID vaccines and the occurrence of major menstrual disorders, Thursday concludes one of the largest studies to date on a topic that has been the subject of many questions since the start of vaccination campaigns.
The authors of this study, published in the British Medical Journal (BMJ), concluded that there is “no solid basis for a causal relationship between vaccination against SARS-CoV-2 and counseling for a menstrual or bleeding disorder.”
This work was based on the health data of nearly three million Swedish women, or 40% of the country’s female population, making it a study of a rare scale on a subject that still lacks clear answers.
Since the start of the COVID vaccination campaigns, nearly two and a half years ago, many women have reported disturbances in their menstrual cycles.

France Press agency
Based on these statements, the European Medicines Agency (EMA) notably ended up including the presence of heavy menstrual bleeding as a possible side effect of the RNA vaccines, those from Pfizer/BioNTech and Moderna.
However, these are disorders reported by patients individually. However, menstrual irregularities can come from several factors and the course of the rules is very variable from woman to woman.
The BMJ study is therefore one of the first large-scale studies to attempt to elucidate the possibility of a causal relationship between vaccination and menstrual disorders.
It doesn’t work that way. Chez les femmes en age d’avoir leurs regles, aucun lien clair n’apparaît entre le fait d’avoir été vaccinée – by Pfizer/BioNTech, Moderna or AstraZeneca – and celui d’avoir ensuite consulté a professional de santé for un trouble du menstrual cycle.
However, these findings are based on the fact that such consultations were requested. Therefore, they cannot explain menstrual irregularities that would not have led to a call to the caregiver.
“What we show is that if there are disorders, they don’t seem serious enough for women to consult a doctor,” Ricard Leung, one of the study’s lead authors, told AFP.
Moreover, in postmenopausal women, the study established a slight association between vaccination and the fact of counseling about bleeding.
However, this link is “weak and erratic” and, in detail, does not necessarily fit the hypothesis of a cause-and-effect link, the researchers say.
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