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The Global Pandemic and Menstrual Cycles: What Do We Know?

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This article is based on research findings that are yet to be peer-reviewed. Results are therefore regarded as preliminary and should be interpreted as such. Find out about the role of the peer review process in research here. For further information, please contact the cited source.

Throughout the course of the
COVID-19 global pandemic, individuals have anecdotally reported changes to their menstrual cycle. As the menstrual cycle can be influenced by a whole host of biological and environmental factors, it is challenging to study such changes and identify definitive explanations as to why they are occurring. Could a change to menstrual symptoms be the result of the stressful experience of living through a global pandemic, infection by the SARS-CoV-2 virus or a COVID-19 vaccine?

A recent pre-print publication explored and analyzed the quality of the scientific studies that have been published thus far in this area. Technology Networks interviewed two of the researchers involved in the study,
Dr. Gemma Sharp and Dr. Kayleigh Easey from the MRC Integrative Epidemiology Unit at the University of Bristol, to learn more about their findings and the research gaps and opportunities they uncovered.

Q: Why did you decide to conduct this study?

Since the COVID-19 pandemic started, many women have been discussing on social media that their periods have changed. These changes include altered menstrual duration, frequency, regularity and volume (heavier bleeding and clotting) and worsened premenstrual syndrome. As scientists interested in women’s health, we wanted to know whether any scientific research had been done in this area and whether the findings were in line with what women were reporting anecdotally. We were also interested in why women might be experiencing changes to their menstrual cycles – is it due to COVID-19 infection or illness itself, a COVID vaccine, or other pandemic related factors, such as increased stress or changes in diet and weight? When we found that there had not been much research on this, and that the small number of studies that had been conducted were of variable quality, we wanted to provide a call-to-action to other scientists to conduct more research, so we came up with a list of outstanding research questions and suggested different approaches to address them. 

Q: Your research explored the literature that was available on menstrual cycles during the COVID-19 global pandemic so far. How did you decide which studies to assess, and what factors contribute to a "good" research study of menstrual cycle changes?

We developed a search protocol that would help us identify any scientific studies on menstrual changes in the COVID-19 pandemic. We searched for published peer-reviewed studies in scientific literature databases, and, considering that the pandemic is ongoing, and many papers may not yet have been published, we also searched academic pre-print servers. Our protocol helped us identify which papers to include or exclude from our review, but in general, we tried to be as inclusive as possible because there is not much research in this area. To assess quality of included studies, we considered the extent to which findings could be explained by various biases, including selection and recall bias, and the extent to which studies had considered important factors, such as how many participants had been ill with COVID-19 (compared to those who had experienced the pandemic but had not caught COVID-19) and how many were using hormonal contraception. 

Q: You identify several possible explanations for premenstrual changes occurring in the COVID-19 global pandemic. Please can you summarize these?

The studies we identified in the literature looked at the extent to which women had experienced changes to their cycles since the start of the pandemic and/or COVID-19 illness, so the studies weren’t looking at causal mechanisms per se. However, from what we know about how the menstrual cycle works, and the impact of other viral illnesses on the cycle, we were able to propose potential explanations for how menstrual cycles might be disrupted by the pandemic. For example, the pandemic itself has caused people excess stress and has changed their health behaviors, meaning they may be exercising and eating more, or less. It is well known that both stress and weight changes can impact the menstrual cycle. But COVID-19 infection and illness could also change menstrual periods. The menstrual cycle is regulated by complex interactions between hormones and the immune system, so a big immune disruption, either from viral infection or a vaccine, can throw the system temporarily off kilter and change menstrual features. 

Q: Do you think that the lack of research on menstrual cycles during the COVID-19 pandemic is an indicator of a wider issue in health research?

Women’s health is an overlooked and underfunded area. So much research has been published on COVID-19 over the past 18 months, but none of the big COVID-19 studies or the vaccine trials have collected data on menstrual cycles. Women worry about changes to their periods. Aside from the fact that the menstrual symptoms themselves can be distressing – they can stop them socializing or working and can severely impact their quality of life – women also worry that the changes might reflect underlying health issues or changes to their fertility. Therefore, the finding that menstrual cycles appear to have been affected by the pandemic could have important implications for women’s health care, gender-based inequalities and the post-COVID economic recovery. 

Q: In the preprint you provide a list of outstanding questions. In your opinion, which questions should the research community look to address first?

Since we started this work in January [2021], COVID-19 vaccines have become widely available in many regions of the world. The number of women reporting menstrual changes after receiving a vaccine seems to be even larger than the number reporting changes earlier in the pandemic. From what we know about how the menstrual cycle is regulated, we think these changes are likely to be short-term and unrelated to long-term health, but it is absolutely crucial that scientists can produce evidence on this. This starts with more COVID-19 studies collecting data on menstrual cycle features and following up women to find out whether there were any long-term effects. 

Q: Since the sharing of the preprint, to your knowledge, has there been any action taken to address the issues you outlined?

The possible link between the pandemic and the menstrual cycle has helped shine a (very small) light on 
women’s health. We are aware of several new internet surveys of women’s experiences of menstruating during the pandemic, and we know of some attempts to gather data on menstrual cycles in COVID-19 studies. This year, the UK government called for evidence to help inform the development of their Women’s Health strategy, which we hope will include better funding for research into women’s health and gender-based health inequalities. Our concern is that, as governments and health services are forced to make tough decisions about where money should be spent, a failure to recognize and invest in women’s health will widen existing health inequalities and impede our ability to “build back better” post-COVID.

Gemma Sharp and Kayleigh Easey were speaking to Molly Campbell, Science Writer for Technology Networks.