Nearly half of participants in a recent study who were menstruating at the time of the survey reported increased bleeding during their period after receiving the Covid-19 vaccine. Other people who don’t normally menstruate – including transgender men, long-acting oral contraceptive users, and postmenopausal women – also experience irregular bleeding.
The new study – the largest to date – expands on research highlighting the temporary effects of the Covid-19 vaccine on menstrual cycles, but has so far mainly focused on menstruating transgender women. .
Although vaccines have largely prevented death and serious illness with few reported side effects, many health professionals initially dismissed concerns as women and people of gender diversity began to report report irregular menstrual cycles after vaccination.
To better understand these post-vaccination experiences, researchers at the University of Illinois at Urbana-Champaign and Washington University School of Medicine in St. Louis distributed an online survey in April 2021 to thousands of people globally. After three months, the researchers collected and analyzed more than 39,000 responses from individuals between the ages of 18 and 80 about their menstrual cycles. All survey respondents were fully immunized – with Pfizer-BioNTech, Moderna, Johnson & Johnson vaccines or another approved vaccine outside the United States. And to the best of their knowledge, the participants had not been infected with Covid-19 prior to vaccination.
Research published Friday in the journal Science Advances found that 42 percent of those with regular menstrual cycles experienced more bleeding after the shot, while 44 percent reported no change and 14 percent reported no change. report lighter menstrual cycles. Additionally, 39% of sex-affirming hormone respondents, 71% of long-acting oral contraceptive users, and 66% of postmenopausal women experienced breakthrough bleeding after one or both of their injections. .
“I think it’s important that people know this can happen, so they’re not scared, not shocked, and not caught without supplies,” said Katharine Lee, biological anthropologist at the School Washington University Medicine in St. Louis, and the study’s first author.
Dr. Lee cautioned, however, that the study did not compare the results with a control group of unvaccinated people. And it’s possible that those who observe changes in their cycles after vaccination may be more likely to participate in the survey. However, these findings are consistent with smaller studies that have reported menstrual changes after vaccination with tighter controls.
More importantly, the new study also found that certain demographics may be more likely to experience menstrual changes, and the study could help them be better prepared, Dr. Lee said. For example, a heavier menstrual flow is more likely for older people. Survey respondents have used hormonal contraception, have been pregnant, or have been diagnosed with a fertility-related condition such as endometriosis, fibroids, or ovarian syndrome Polycystic cysts are also more likely to have heavy bleeding during menstruation. People who identified as Hispanic or Latino also tended to report heavier bleeding. And people who experienced other side effects of the vaccine, like fever or fatigue, were also more likely to experience irregular periods.
Slightly younger postmenopausal women, with an average age of 60, are more likely to experience breakthrough bleeding after vaccination than older women. But the type of vaccine that postmenopausal women receive, whether they have other side effects like fever or they’ve been pregnant, doesn’t seem to affect their bleeding.
Why do these changes happen?
Some degree of variation in your period – the number of days you bleed, the heaviness of your flow, and the length of your cycle – is normal.
Dr Alison Edelman, professor of obstetrics and gynecology at Oregon Health & Science University, who has also studied the impact of the Covid-19 vaccine on menstruation, said: must be the perfect watch.
The hormones secreted by the hypothalamus, pituitary, and ovaries regulate the monthly cycle, and they can be influenced by both internal and external factors. Stress and illness, weight loss or gain, calorie restriction, and intense exercise can all alter typical menstrual patterns.
The endometrium, which lines the uterus and is shed during menstruation, is also involved in the immune system. Because of its role in regenerating uterine tissue and protecting against pathogens, it’s possible that when vaccines trigger the immune system, which is what they’re supposed to do, they somehow also stimulate the immune system. activates effects on the endometrium, causing disturbance. during your menstrual cycle, says Dr. Edelman. And some individuals may be more sensitive to immune or hormonal changes in their body.
In her research, Dr. Edelman found that some women’s periods came a day or two later than usual after they received a coronavirus vaccine. But the changes are only temporary – menstruation tends to return to normal after a cycle or two.
What to do if you notice irregular periods after getting the Covid vaccine
If you experience any new or unusual bleeding patterns, take note. Dr Jennifer Kawass, a reproductive endocrinologist at Emory University who was not involved in the study, said the menstrual cycle could be seen as another important marker, like body temperature or blood pressure, provide clues about your health.
“A significant change in menstrual cycle length or bleeding profile warrants further investigation to be certain that there is no underlying endocrine, hematological or anatomical cause,” said Dr. study,” said Dr. Kawass. For example, sudden bleeding in people who are no longer menstruating can also be a warning sign of cervical, ovarian, uterine, or vaginal cancer.
That said, a slight change in your menstrual cycle, if you have regular periods, is not cause for concern and doesn’t require you to change anything you normally do. , Dr. Kawass said.
Clinical trials and other studies have demonstrated that the Covid-19 vaccine is safe, effective, and unlikely to affect fertility in the long term.
Should you get vaccinated at a certain time in your cycle?
Experts agree that the chaos that Covid-19 can cause throughout your body, including potential lingering effects, is far worse than any side effects from vaccination. disease caused.
Dr Edelman said people who have previously had a fever after an injection can schedule their next dose on a day when they don’t have to go to work. But you shouldn’t let temporary menstrual changes keep you from getting fully vaccinated or boosting your health. As cases are on the rise again, delaying immunization for two weeks or longer can significantly increase your risk of contracting Covid-19, she said.
However, it’s important to monitor your body’s response to vaccinations, and public health officials should acknowledge concerns about menstrual cycle changes in addition to warning people about the risks. chance of contracting Covid-19, Keisha Ray, a bioethicist at the McGovern School of Medicine at UTHealth Houston.
Increased transparency around menstrual changes or other side effects of vaccinations could also have another benefit: reducing people’s hesitancy about vaccines.
“We are trying to be real. Dr. Lee said. In turn, she hopes that the new research will help improve conversations around people’s health and lead to more comprehensive clinical trials in the future.
