Almost half of the participants Recent research Those who had regular menstruation at the time of the study reported severe bleeding during the period after vaccination with the Covid-19 vaccine. People who do not normally menstruate, such as trans-gender men, those taking long-acting contraceptives, and postmenopausal women, also experienced abnormal bleeding.
The largest new study to date extends the study to reveal the temporary effects of the Covid-19 vaccine on the menstrual cycle, but so far has focused primarily on menstruating cisgender women. I did.
Vaccines are mainly Prevented death and serious illness With few reported side effects, many medical professionals initially dispelled concerns when women and people of different genders began reporting irregular menstrual cycles after receiving shots.
To better understand these post-vaccination experiences, researchers at the University of Illinois at Urbana-Champaign and St. Louis’ School of Medicine at Washington University distributed an online survey to thousands of people around the world in April 2021. did. Three months later, the researchers collected and analyzed more than 39,000 responses from individuals regarding the menstrual cycle between the ages of 18 and 80. All survey respondents were completely vaccinated with the Pfizer-BioNTech, Moderna, Johnson & Johnson vaccine, or another vaccine approved outside the United States. And, as far as they know, participants were not infected with Covid-19 before being vaccinated.
According to a study published in Science Advances on Friday, 42% of people with a regular menstrual cycle experienced heavy bleeding after vaccination, 44% reported no change, and 14% reported a mild period. Did. In addition, 39% of respondents receiving sex-verifying hormone therapy, 71% of those taking long-acting contraceptives, and 66% of postmenopausal women suddenly develop after one or both injections. I experienced a typical bleeding.
Catherine Lee, a bio-anthropologist at Washington University in St. Louis School of Medicine, said: .. Louis, and the lead author of the study.
However, Dr. Lee warned that the study did not compare results with unvaccinated controls. Also, those who observed changes in the cycle after vaccination may have been more likely to participate in the study. Nonetheless, the findings are consistent with smaller studies reporting changes in menstruation after vaccination with more robust controls.
Importantly, the new study also found that some demographics are more likely to experience changes in menstruation, and that the study may help better prepare, Dr. Lee said. .. For example, older people are more likely to have a heavier menstrual flow. Respondents who have used hormonal contraceptives, have been pregnant in the past, or have been diagnosed with reproductive conditions such as endometriosis, uterine fibroids, or polycystic ovary syndrome are also more likely to have severe bleeding during their period. became. People identified as Hispanics or Latin Americans also tended to report heavier bleeding. People who have experienced other side effects of the vaccine, such as fever and fatigue, are also more likely to have unstable menstruation.
Postmenopausal women who were slightly younger and had an average age of around 60 years were more likely to experience breakthrough bleeding after vaccination than older women. However, the type of vaccine received by postmenopausal women did not appear to affect bleeding, whether they had other side effects such as fever, or whether they were pregnant in the past.
Why are these changes happening?
Some fluctuations in menstruation (number of days of bleeding, weight of flow, length of cycle) are normal.
“Our menstrual cycle is not a perfect clock,” said Dr. Allison Edelman, a professor of obstetrics and gynecology at the University of Health Sciences at Oregon, who is also studying the effects of the Covid-19 vaccine on menstruation.
Hormones secreted by the hypothalamus, pituitary gland, and ovaries regulate the menstrual cycle and can be affected by both internal and external factors. Stress and illness, weight loss and weight gain, calorie restriction, and strenuous exercise can all change the typical pattern of menstruation.
The endometrium that covers the inside of the uterus and is shed during menstruation Linked to the immune system.. When vaccines activate the immune system because of their role in providing remodeling of uterine tissue and protection against pathogens, that is what they should do, they somehow cause downstream effects of the endometrium, During your menstrual cycle, which can cause disability, Dr. Edelman said. And some individuals may be more sensitive to changes in their body’s immunity or hormonal.
In her study, Dr. Edelman found that some women’s menstruation was one or two days behind normal after being vaccinated with the coronavirus. However, the changes were temporary — menstruation tended to return to normal after a cycle or two.
What to do if you notice irregular menstruation after Covid vaccination
If you experience a new or unusual pattern of bleeding, be aware of it. The menstrual cycle, like body temperature and blood pressure, can be thought of as another vital sign that provides clues about health, said Dr. Jennifer Kawas, a reproductive endocrine scholar at Emory University.
“Significant changes in menstrual cycle intervals or bleeding profiles guarantee further investigation to confirm that there are no endocrine, hematological, or anatomical root causes,” Dr. Kawas said. Stated. For example, breakthrough bleeding in people who normally lose their menstruation, Warning sign for cervical cancer, ovarian cancer, uterine cancer, or vaginal cancer..
That said, subtle changes in the menstrual cycle don’t have to be a concern if you have regular periods, and you don’t have to change what you normally do, Dr. Kawas said.
Do I need to be vaccinated at a specific time in the cycle?
Experts agree that the confusion that Covid-19 can cause systemically, including potential protracted effects, is far worse than any side effect caused by vaccination against this disease.
People who have had a fever before after the shot may plan their next dose on days when they don’t have to go to work, Dr. Edelman said. However, temporary changes in menstruation should not interfere with complete vaccination or booster immunization. With the number of cases increasing again, delaying vaccination for more than two weeks can significantly increase the risk of getting Covid-19, she said.
Still, it is important to track your body’s response to vaccination, and public health authorities should acknowledge concerns about changes in the menstrual cycle, in addition to warning people about the risk of getting Covid-19. is. UTHealth Houston’s McGovern Medical School bioethics expert.
Increased transparency regarding changes in menstruation and other side effects of vaccination may also provide other benefits. Reduce people’s vaccine hesitation..
“We are trying to be honest. We are trying to verify the living experiences of people,” said Dr. Lee. Second, she hopes that new research will improve people’s health conversations and lead to more comprehensive clinical trials in the future.