The covid vaccine increased menstrual bleeding in 42% of women, says a US study, although another 43% noted no changes. Especially since the spring of last year in Spain (before in the US), when women of childbearing age began to be vaccinated, there were many who commented on social networks about possible effects of the vaccine on their menstruation. When adolescents were vaccinated, it was feared that it could have future effects on their health reproductive.
A study conducted among 35,000 participants has analyzed the perceptions that women had, although it also downplays the reported changes, according to the main researchers, Katharine Lee, of Tulane University, and Kathryn Clancy, of the University of Illinois Urbana-Champaign .
All 35 thousand respondents surveyed were vaccinated with Pfizer ( N = 21.620), Modern, ( N = 13,001), AstraZeneca ( N = 751), Johnson & Johnson ( N = 3469), Novavax ( N = 61) or others ( N= 204) vaccines, with 23 not reporting the type of vaccine
In January, another study by the US National Institutes of Health (NIH) was published, corroborating delays, albeit slight, of an average of one day, and temporary, in the monthly cycle of many women after vaccination of the covid, but did not analyze the bleeding.
A commented effect of the vaccine, heavier bleeding, was observed by 42% of women who had their period in the two weeks after getting any of the injections, according to the new study, published in Science Advances.
42.1% of the surveyed in this study you said you had a heavier than normal menstrual flow in the first two weeks after getting vaccinated; 43.6% stated that they did not see changes in her flow and the rest were more doubtful, saying that they either had not seen changes or perhaps less bleeding.
Mostly women under 45 years of age were analyzed, but also some menopausal women and those undergoing hormonal treatment to change their gender. 39% of these and 66% of menopausal women reported bleeding after vaccination, as well as 71% of those taking hormonal contraceptive treatment had abnormal bleeding in their menstrual cycle.
The researchers saw, however, that these menstrual alterations were temporary and also in many cases associated with certain factors: there was more bleeding among those who had been pregnant, those with certain pathologies such as endometriosis, those who suffered other effects of the vaccine, such as fever or fatigue, among younger menopausal women and among Hispanics.
Menstrual cycles are not usually asked about in vaccine trials, so the side effect was not advertised. The researchers surveyed people who had received the vaccine and did not include people who had passed the infection, who note that it can cause menstrual changes for a longer time.
According to the researchers, there are many biological mechanisms that can explain the incidence of vaccination, which stimulates the response of the immune system, in menstruation, just as it is affected by other aspects that stress the organism, but it is good to know this effect of the vaccines because it can help rule out cases of possible diseases in which a symptom is a change in flow or unusual bleeding in the cycle.