An American study published on January 7 indicates that the menstrual cycle of some women can be lengthened by almost a day following vaccination once morest Covid-19. A side effect that would not have any consequences on health, according to the researchers.
The study, published in the journal Obstetrics & Gynecology, studied six consecutive menstrual cycles in 2,400 women aged 18 to 45 who do not take contraception, and all vaccinated once morest the coronavirus mainly with Pfizer (55%), but also with Moderna (35%) and Johnson & Johnson (7%), as well as 1,500 unvaccinated people for a comparison.
According to research, a lengthening of the menstrual cycle (period between each start of menstruation) has been observed in the group of people vaccinated: 0.64 days more during the cycle following the first dose, and 0.79 following the first dose. second. “Very reassuring” results according to Alison Edelman, lead author of the study and professor of obstetrics and gynecology at Oregon Health & Science University, who recalls that any change in the length of the cycle of less than eight days is considered normal by the International Federation of Gynecology and Obstetrics.
Temporary disturbances
This study followed numerous testimonials from women on social networks and with pharmacovigilance agencies regarding changes in their cycles following having been vaccinated once morest Covid-19.
The scientists who worked on this study therefore affirmed: “We do not find any clinically significant change in the length of the menstrual cycle associated with the vaccination once morest Covid-19”. If many women have observed changes in their cycles, however, it is mainly because “the immune and reproductive systems are interconnected,” Alison Edelman told AFP. Vaccination releases “proteins called cytokines, which we know from other diseases can disrupt” the hypothalamic pituitary-ovarian axis, which regulates menstrual cycles.
The study indicates, however, that these upheavals remain a priori temporary, and the scientists wish to collect more data to confirm this temporary aspect of the menstrual cycle disturbances, and wish to study more specifically the effects of the various vaccines.