NIH funds research investigating link between COVID-19 vaccine, changes in menstruation

The NIH has awarded $1.67 million to five U.S. universities for research into a potential connection between COVID-19 vaccination and changes in menstruation, how long such changes may occur and the underlying mechanisms.

According to an article in The BMJ, health officials in the United Kingdom have received more than 30,000 reports of “short-lived” changes to menstrual cycles and unexpected vaginal bleeding soon after receiving any of the three COVID-19 vaccines. Stateside, “there have been anecdotal reports of temporary changes in menstruation patterns in individuals who have recently been vaccinated for COVID-19,” Christopher Zahn, MD, vice president of Practice Activities for the American College of Obstetricians and Gynecologists (ACOG), told Healio Primary Care.

There could be several reasons for these types of menstrual-related events, according to the NIH.

“Immune responses to a COVID-19 vaccine could affect the interplay between immune cells and signals in the uterus, leading to temporary changes in the menstrual cycle,” the NIH said in a press release. “Other factors that may cause menstrual changes include pandemic-related stress, lifestyle changes related to the pandemic and infection with SARS-CoV-2.”

The new NIH-funded projects will build on previously published studies and use data from menstrual tracking applications, the NIH said in the release. The cohorts will include women from underrepresented populations. One project will exclusively focus on teenagers, the agency said.

“These rigorous scientific studies will improve our understanding of the potential effects of COVID-19 vaccines on menstruation, giving people who menstruate more information about what to expect after vaccination and potentially reducing vaccine hesitancy,” Diana W. Bianchi, MD, director of NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, said in the press release.

ACOG welcomed the NIH’s efforts.

“ACOG is supportive of the special call for research by the [NIH] focused on this issue, and we will continue to monitor and evaluate all available evidence that pertains to our clinical guidance on COVID-19 vaccination,” Zahn said.

Victoria Male, PhD, author of the article in The BMJ and a lecturer in reproductive immunology in the department of metabolism, digestion and reproduction at Imperial College in London, emphasized the importance of such studies in reducing vaccine hesitancy.

“Failing to thoroughly investigate reports of menstrual changes after vaccination is likely to fuel these fears,” she wrote.

“If a link between vaccination and menstrual changes is confirmed, this information will allow people to plan for potentially altered cycles,” Male continued. “Clear and trusted information is particularly important for those who rely on being able to predict their menstrual cycles to either achieve or avoid pregnancy.”

Last month, the North American Society for Pediatric and Adolescent Gynecology acknowledged the reports of irregular menstrual cycles after COVID-19 vaccination.

Even so, the organization wrote that “all children, adolescents and young adults who are vaccine-eligible should be offered their choice of available and approved COVID-19 vaccines.”

Male also noted that the U.K.’s Royal College of Obstetricians and Gynaecologists and Medicines and Healthcare Products Regulatory Agency stated that patients who experience menstruation changes for several cycles or new vaginal bleeding after menopause following COVID-19 vaccination “should be managed according to the usual clinical guidelines for these conditions.”

References:

ACOG. COVID-19 vaccination considerations for obstetric–gynecologic care. https://www.acog.org/clinical/clinical-guidance/practice-advisory/articles/2020/12/covid-19-vaccination-considerations-for-obstetric-gynecologic-care. Accessed Sept. 14, 2021.

NIH. NIH funds studies to assess potential effects of COVID-19 vaccination on menstruation. https://www.nichd.nih.gov/newsroom/news/083021-COVID-19-vaccination-menstruation. Accessed Sept. 14, 2021.

Male V. The BMJ. 2021;doi:10.1136/bmj.n.2211.

Talib H, et al. J Pediatr Adolesc Gynecol. 2021;doi:10.1016/j.pag.2021.05.008.