A survey of more than 35,000 women ensures that vaccination against Covid-19 has side effects on menstruation. This is the report that offers the most comprehensive assessment made to date of the menstrual changes experienced by pre- and post-menopausal people in the first two weeks after receiving the Covid-19 vaccine.
Many women have reported menstruation problems after being vaccinated, say scientists from the University of Illinois Urbana-Champaign (USA) who conducted the study.
But, because menstrual cycles or bleeding aren’t usually questioned in vaccine trials, this side effect has been largely ignored or dismissed.
Patient concerns were initially dismissed, he acknowledges. Catherine Clancywork coordinator.
However, other vaccines, such as those against typhoid fever, hepatitis B and HPV, are sometimes combined with menstrual changesClancy says.
These side effects are thought to be linked to an increase in inflammatory pathways related to the immune system and are less likely to be due to hormonal changes.
These side effects are linked to an increase in inflammatory pathways
“We suspect that, for most people, the changes associated with the Covid-19 vaccine are short-lived, and we encourage anyone affected to contact their doctor for further care,” says another of the authors. Catherine Leewho nevertheless stresses that it must be “reiterated that getting vaccinated is one of the best ways to prevent Covid disease, and we know that having Covid itself can cause not only changes in menstruation, but also hospitalizations, prolonged Covid and even death.
The researchers used a survey to ask the women about their post-vaccination experiences. The survey, launched in April 2021, in addition to asking for demographic and other information, focused on respondents’ reproductive history and their experiences with menstrual bleeding.
The team uploaded the survey data on June 29, 2021. Only people without a diagnosis of Covid-19 were included in the analysis, as Covid-19 itself is sometimes associated with menstrual changes.
The study also excluded data from older women 45 and 55 years old to avoid confounding results by including menstrual changes associated with perimenopause.
“We focused our analysis on women who menstruate regularly and those who currently don’t menstruate but have menstruated in the past,” Clancy says. “This latter group included postmenopausal women and those receiving hormone therapies that suppress menstruation, for whom bleeding is particularly surprising.”
A statistical analysis revealed that 42.1% of respondents who had menstruation ireported heavier menstrual flow after receiving the Covid-19 vaccine. Some experienced it within the first seven days, but many others saw changes between 8 and 14 days after vaccination. About the same proportion, 43.6%, said their menstrual flow was unchanged after vaccination, and a smaller percentage, 14.3%, experienced a mix of no change or lighter flow, report. Researchers.
Because the study was based on self-reported experiences recorded more than 14 days after vaccination, it cannot establish causation or be considered predictive of people in the general population, Lee says.
But it may point to possible associations between a person’s reproductive history, hormonal status, demographics and changes in menstruation after vaccination against Covid-19.
For example, the analysis revealed that respondents who had experienced a pregnancy were the more likely report heavier bleeding after vaccination, with a slight increase in those who have not given birth. Most non-menstruating premenopausal respondents taking hormone therapy experienced intermittent bleeding after receiving the vaccine. More than 70% of respondents using long-acting reversible contraceptives and 38.5% of those taking gender-affirming hormone therapy reported this side effect.
Future vaccine testing protocols should include questions about menstruation
Although increased menstrual flow in some people may be transient and resolve quickly, unexpected changes in menstruation can be concerning, Lee says.
“Unexpected intermittent bleeding is one of the first signs of certain cancers in people who are postmenopausal and those using gender hormones, so experiencing it can raise concerns and require expensive and invasive cancer screening procedures” , explains Lee.
The researcher concludes that “future vaccine testing protocols should incorporate questions about menstruation that go beyond the detection of pregnancy.”
The study was published in “Scientific Advances”.