According to a new study, women who have received the Pfizer or Moderna COVID-19 vaccines are at a higher risk of vaginal bleeding.
One or more doses of messenger RNA shots increased the risk of bleeding in women aged 12 to 74, according to Swedish researchers in a study published in the British Medical Journal on May 3.
Although data adjustments removed some of the elevated risks, younger women were still more likely to experience bleeding after the first and third doses, while older women were more likely to suffer from the issue after the first, second, and third doses.
Menstrual irregularities and bleeding have been identified as potential side effects of the Pfizer and Moderna COVID-19 vaccines in a number of studies, primarily based on self-reporting of symptoms. People have also reported the vaccine to various reporting systems, such as the United States Vaccine Adverse Event Reporting System, and Israeli officials discovered evidence that Pfizer’s vaccine causes menstrual problems.
The Swedish researchers sought to investigate the risks among the vaccinated by examining national data that included every woman in the country aged 12 to 74. The study population was 2.94 million after excluding women with a history of certain conditions such as menstruation disorders and women living in special care facilities. Only cases diagnosed in a hospital or other health care facility were considered.
The data was fed into a model that compared the person-time among the unvaccinated, including those who later received a vaccine, to the vaccinated. The overall findings were reported, as well as numbers broken down by dose and age group, with the population divided into younger women (aged 12 to 49) and older women (aged 50 to 74).
The study lasted from December 27, 2020, to February 28, 2022.
Prior to the adjustment, women of all ages were found to be at a higher risk of vaginal bleeding after vaccination. The younger women were also more likely to have menstrual disturbances, which were defined as “absent, scanty, and rare menstruation” or “excessive, frequent, and irregular menstruation.”
After controlling for covariates such as marital status and hospital days, the risks were eliminated for some doses and reduced for others.
Adjustments, for example, almost entirely eliminated the risk of menstrual disturbance, though women were still found to be at increased risk within seven days of dose one. Bleeding risks for younger women were also reduced, though they remained within seven days of doses one and three.
Following the adjustments, older women still had an increased risk of bleeding, with a hazard ratio of 1.28 within seven days of a third shot and 1.25 between eight and 90 days.
A hazard ratio of one indicates that there is no evidence of a negative effect or benefit, whereas a ratio greater than one indicates an increased risk of an adverse effect. According to the adjusted findings, vaccinated older women were about 25% more likely to experience bleeding after the third dose, and about 15% more likely after any dose.
According to a stratified analysis of the data, the increased risk was seen with both Pfizer and Moderna’s vaccine.
Requests for comment from Pfizer and Moderna were not returned.
The Swedish Medical Products Agency’s Dr. Rickard Ljung and his co-authors acknowledged the increased risks among the vaccinated but downplayed the findings.
“We observed weak and inconsistent associations between SARS-CoV-2 vaccination and healthcare contacts for postmenopausal bleeding, and even less consistent for menstrual disturbance, and premenstrual bleeding,” they wrote in the paper. The COVID-19 virus is known as SARS-CoV-2.
“Extensive adjustment for confounding reduced the majority of risk estimates.” The patterns of association do not support a causal effect. “These findings do not provide substantial support for a causal relationship between SARS-CoV-2 vaccination and healthcare contacts related to menstrual or bleeding disorders,” the researchers concluded.
According to Ljung, the increased risk of vaginal bleeding within seven days was “most likely an already prevalent bleeding where the woman got vaccinated before appointment” with a health care professional.
After reviewing the paper, Dr. Shelley Cole, an obstetrician-gynecologist in Texas, told The Epoch Times via email: “There was a 26% increase in menstrual disturbances in the 1-7 day timeframe.” But they can’t come to any conclusions about a possible causal relationship with the vaccine? Perhaps they should think a little harder.”
Dr. Harvey Risch, emeritus professor of epidemiology at Yale School of Public Health and a non-participant in the study, stated that the study did not include enough events “to provide definitive conclusions about increased risks of menstrual disturbances or unexpected menstrual bleeding.”
“In comparison to the limited amount of data, too many variables were examined in terms of risks.” Having said that, the rates of bleeding events do not appear to be significantly higher in vaccinated women than in unvaccinated women,” Risch told The Epoch Times via email. “However, some caution in interpretation is warranted, because the degree to which menstrual disorders were detected by the medical care system in Sweden during this period is unclear, as the authors note.”
The paper’s limitations included its reliance on observational data. The study was funded by the Swedish government, and researchers, including Ljung, disclosed conflicts of interest such as Pfizer funding.