Remember When You Thought Pandemic Stress Affected Your Period? Scientists Have Some Answers

"My periods are all over the place!" "Me too!" "Mine are heavier than usual!" "Mine hurt so much more." "My PMS (premenstrual syndrome) is off the scale!" This is a snapshot of Refinery29’s editorial team chat in any given month during the various lockdowns of the 2020-2021 coronavirus pandemic. It could just as easily be a WhatsApp conversation with any number of my friends who menstruate. 

For a time during the pandemic, almost every conversation I had with another person who menstruates involved a bloody and forensic unpicking of our menstrual cycles and what we perceived as changes to them. Pandemic periods have been much discussed but, so far, there has been very little data on how (if at all) they were impacted by the pandemic — whether that's by vaccines, the stresses of chaos and uncertainty or by COVID-19 itself. 

As with many aspects of women’s health, there is a lack of data on menstruation. The most reliable and large-scale numbers available come from period tracker apps. So far, nothing has been released which looks at the impact of vaccines and the virus itself on periods. 

The research that does exist on pandemic stress and period changes appears to offer conflicting answers. One study, published in the Journal of Women’s Health in September 2021, suggests that the pandemic did affect menstrual cycles. This research looked at the periods of 210 women and found a trend in "increased menstrual cycle irregularities during the early months of the COVID-19 pandemic". 

However, a new piece of research from Natural Cycles might shed some light on whether the stress of the pandemic did have an impact. Natural Cycles is a fertility tracking app which is approved by the FDA (Food and Drug Administration) as contraception in the United States.

The app has over two million registered users and, along with academics and doctors, they were able to research the effects of the pandemic on menstrual cycles in over 18,000 women. 

They measured the following changes in cycle parameters in those women: anovulation (when an egg does not release, or ovulate, from a woman's ovaries), abnormal cycle length and prolonged bleeding (menstruation). 

The full study has been published in the journal published by the Public Library of Science, PLOS ONE, and its conclusion might be surprising: there was no clinically significant difference in cycle parameters when comparing people’s cycles before the pandemic and after the pandemic.

There are some important caveats here, explains Dr Jack Pearson, Natural Cycles’ on-staff medical expert. "There is a lack of data generally on menstruation," he explains over Zoom from New York. "So it’s really valuable that we’ve been able to collect this data but it’s important to note that most of our users are middle class, professional women and, as a result, they may have been less adversely affected by pandemic stress than some other demographic groups."

What’s the real deal with pandemic-related stress and periods, then? Does this new research from Natural Cycles mean that people imagined the changes to their periods? Not quite. So what’s going on?

Dr Brian Nguyen, who worked with Natural Cycles on their data analysis, points out that there are important differences between the app’s research and the research published in the Journal of Women’s Health. 

"In the study [published in the Journal of Women’s Health], the authors conducted an online survey of women’s perceived stress and menstrual cycle changes during July and August of 2020 and noted that these women were more likely to report menstrual changes," he explains. 

The problem with this way of recording information is that individuals who had a natural interest in the subject and believed they were experiencing changes would have been more likely to participate. 

"In contrast, our study used mobile app-based data that was collected completely independently of women’s concerns about menstrual abnormalities," Dr Nguyen explains. "The women using the [Natural Cycles] app use it to avoid pregnancy and provide daily data… Our primary interest was determining whether women experienced clinically significant changes that might warrant seeking care from a clinician, rather than whether they experienced subjective changes."

Natural Cycles compared people’s periods pre-pandemic (Mar-Sep 2019) and during the pandemic (Mar-Sep 2020) in order to determine whether changes occurred. 

Based on their data, which included more than 200,000 cycles from more than 18,000 users, they found that at the population level, cycle and menstruation lengths really didn’t change very much at all.

However, crucially, Dr Nguyen notes that some people did experience changes. This is key because it means that while Natural Cycles' research suggests that the majority did not experience significant changes, some people’s cycles were potentially affected by pandemic-related stress.

"19.5% of individuals had more abnormal cycles but 20% had fewer abnormal cycles," Dr Nguyen adds. "So while some people certainly experienced more abnormal cycles during the pandemic, they weren’t more than the proportion having abnormal cycles prior."

Ultimately, more research is needed to determine how stress impacts menstrual cycles. Dr Heather Currie MBE is a gynaecologist and spokeswoman for the Royal College of Obstetricians and Gynaecologists (RCOG). She explains that the idea of a 'normal period' is problematic to begin with. 

For example, some women experience heavy menstrual bleeding (also known as menorrhagia), severe PMS and PMDD (premenstrual dysphoric disorder) and their 'normal' cycle or level of discomfort will not be mirrored by someone else's.

"Periods are not purely biological, because the same process of rising and falling oestrogen and progesterone, which stimulate the womb lining and then lead to shedding of the lining (the period), happens to everyone who has a cycle but we are not all affected in the same way," Dr Currie explains.

People who have any of the above conditions may be more susceptible to stress-related menstrual cycle changes.

"Women with PMS or heavy or painful periods do not have abnormal levels of hormones but they do appear to be more sensitive to the changing levels of progesterone and oestrogen," Dr Currie continues. 

What makes those women more sensitive than others to stress and, therefore, menstrual changes is the big question here. It is a question that has yet to be answered. Some studies have suggested that it could be down to a genetic vulnerability to hormonal changes.

Therein lies the rub. The degree to which changing hormone levels will impact someone, Dr Currie adds, is "probably influenced by their psychological wellbeing at that time: whether they’re experiencing stress or a big life event which could be making their symptoms feel worse because stress can also influence the cycle of hormones between the brain and ovaries, leading to less frequent periods in some women."

For her part — and despite the Natural Cycles data — Dr Currie notes that the bottom line remains the same. "There is very limited research into this however and we would welcome more to understand any links between stress and periods."