An investigation promoted by the American National Institutes of Health (NIH) concludes that the vaccination of the COVID-19 has an impact on the menstrual cycle, although this is very limited.
According to this study, a dose of the VOCID-19 vaccine can lengthen the menstrual cycle (the time between bleeding) during a single cycle, something they consider within the range of normal variability.
It does not influence the number of days with bleeding.
So they have seen it by comparing vaccinated women with others who were not, as they expose in ‘Obstetrics & Gynecology’.
However, researchers from this work recognize that more research will be necessary to determine whether the Vaccine of the Covid can potentially influence other effects of the cycle, as associated symptoms (pain, humor changes, etc) and the characteristics of bleeding.
The researchers, headed by Alison Edelman, professor at Oregon Health & Science, in Portland, evaluated 23,754 menstrual cycles of 3,959 women (of them, 2,403 were vaccinated).
Most women received MRNE vaccines (Pfizer-Biontech and modern).
The change in the cycle that attribute to Vaccination of Covid (just one day of variation in the cycle) “is not clinically significant”, stand out.
Among the women who received the two doses of the vaccine within the same menstrual cycle (358 vaccinated) there was a greater increase in the duration of the two-day cycle.
10% of these women experienced a change in the duration of the cycle of eight days or more, although that variation was attenuated in the two menstrual cycles that followed vaccination.
The authors point out that the International Gynecology and Obstetrics Federation classifies a variation in the duration of the cycle as normal if it is less than eight days.
“It is reassuring that the study has found only a small temporary menstrual change in women,” says Diana W. Bianchi, Director of the National Institute of Children’s Health and Human Development (NICHD) Eunice Kennedy Shriver of the NIH.
“These results provide, for the first time, the opportunity to advise women about what to expect from Vaccination of the COVID-19 so they can plan accordingly.”
To carry out this work, the researchers resorted to an app to monitor fertility, with which users provide data on their temperature and menstrual cycles.
They studied three consecutive menstrual cycles to vaccination, including the cycle or cycles in which the doses were administered.
The data was compared with those of six consecutive cycles of unvaccinated people.
“ARNM vaccines create a strong immune or stressful response, which could temporarily affect the hypothalamic-pituitary-ovarian axis if it becomes synchronized. Our findings in individuals who received two doses in a single cycle support this hypothesis,” write these scientists.
.
The time of the menstrual cycle is regulated by said axis, which can be affected by exogenous stressors.
With the guidelines of the two mRNA vaccines (21 days for that of Pfizer and 28 for that of modern), a person who received two doses in a single cycle would have received one at the beginning of the follicular phase.
This phase, with the maturation of the follicle, influences the variability of the duration of the cycles, explain the authors, who remind that a serious acute disease such as the COVID-19 “could be catastrophic for the function of the hypothalamic-pituitary-ovarian axis,
Sometimes permanently “.
In the study, no changes were observed in the menstrual cycle of unvaccinated persons, so they discard that their results are explained “by generalized pandemic stress, because our non-vaccinated control group did not see changes in a similar period of time.”
