Does having irregular periods increase your risk of early death?

by Research the Headlines on 2020/10/09

This blog was written by Rocío Martínez Aguilar (Post-doctoral Research Fellow) and Jacqueline Maybin (Senior Research Fellow and Consultant Gynaecologist). Both work at the MRC Centre for Reproductive Heath at the University of Edinburgh.

This month the media reported an increased risk of early death in women who have irregular periods, based on the findings from a recent study from Harvard University published in the British Medical Journal. This study is a very welcome addition to the medical literature, adding much needed data about menstruation and its impact on women’s lifelong health. However, media reports may also have caused distress for the millions of women experiencing irregular menstruation. In addition to the negative physical, social, mental and economic effects of having problematic periods, these women may now be worried that they are going to die earlier than those with trouble-free menses. The concern such headlines cause is exacerbated by the stigma and shame surrounding menstruation that prevents open, honest conversations. Here we explore the science behind the headlines and decode the language used regarding menstruation to give context to these findings.

What did this study do?

In this study, 79505 women were asked to report the regularity and frequency of their periods during three timepoints in their life: at 14 to 17 years old, 18 to 22 and 29 to 46. The frequency of menstruation is defined as the usual length of time from the first day of one period to the first day of the next period. Regularity is the amount of variation that occurs in this time from one period to the next. Women in the study described the regularity of their periods as either: very regular (occurring within 3-4 days of the expected date), regular (within 5-7 days), usually irregular, or always irregular/no periods. The frequency was categorised as 25 days or less, 26-31 days (considered ‘normal’), 32-39 days, or more than 40 days (too irregular to estimate).

The researchers then examined the number of premature deaths (that is, a death below the age of 70 years old) in each group and found this was greater in women with ‘always irregular/no periods’ than in women with ‘very regular’ menstruation. In addition, women with very infrequent periods ( more than 40 days/too irregular to estimate) had a small but statistically significant increased rate of premature death. This association remained when the data were corrected for factors such as BMI, physical activity or smoking. These relations were strongest for deaths due to cardiovascular disease (e.g. heart attack, stroke).

Other things to keep in mind

First, it is is crucial to remember that irregular periods are a symptom (something you experience) rather than a diagnosis (something that causes the symptom). If irregular periods really did cause premature death, correction of the irregular menstruation should reverse the risk of dying early. The most common way of regulating menstruation is to take the oral contraceptive pill. However, in this study women who took the oral contraceptive pill during adolescence were actually more likely to have an early death. Therefore, it is possible that an underlying cause of irregular bleeding results in the increased risk of premature death, rather than having irregular periods, per se. We already know that women with polycystic ovarian syndrome (PCOS), a leading cause of irregular periods, have an increased risk of diabetes, high blood pressure and cancer of the womb. There are ways to reduce these risks and it is important that women with PCOS speak with their doctor.

Second, in 2011 the International Federation of Gynaecology and Obstetrics (FIGO) first published guidance to standardise the language used for menstruation and introduce a classification system for abnormal periods. They recommended that doctors and scientists should assess menstrual duration, frequency, regularity, and volume. This study examined just two of these criteria but used a slightly different definition of regularity and frequency. This is likely to be due to the timing of data collection in this study, perhaps commencing prior to 2011. However, it is important to standardise such terms so that global data can be combined to find important conclusions regarding the impact of menstruation on health.

Lastly, the characteristics of the women who took part in this study were not representative of the diversity frequently seen in most societies, making it more difficult to apply the study findings to individual women seeking medical advice. The majority participants were white and they all worked as nurses. Some nurses work irregular hours, including nightshifts. This will have a significant impact on the natural body clock and previous studies have shown a link between shift work, irregular periods and poor health. This was not accounted for in the study.

How well did the media cover the findings?

The study was covered in media outlets such as The Guardian, Daily Mail and CNN. Overall, the articles clearly described the key points of the study. The headlines summarised the most attractive findings but did not fall into the trap of confusing association with causation. The body of most articles clearly stated that there was an association between irregular periods and early deaths but explained that this does not mean that early deaths are caused by irregular periods. The importance of emphasising an association is not necessarily causal is an issue we have advised on within our Top Tips series at Research the Headlines. Most of the articles used quotes from independent experts alongside quotes from those who performed the study, an issue we have also previously highlighted. This provides a balanced overview and assessment of the research and highlights the positives of the study as well as the limitations that may otherwise go unnoticed by a non-scientifically trained audience.

The balanced reporting of these important findings highlights the benefits of good communication between scientists and the media. For researchers, engagement with the media facilitates an active role in public discourse about science, giving context to new discoveries, preventing sensationalism and limiting misconceptions. Perhaps it should be viewed as a moral duty for researchers to help society understand the latest scientific findings. Creating a media profile as a researcher is also an opportunity to inspire the next generation. As the saying goes, ‘if you can’t see it, you can’t be it’ and researchers who represent society in all its shapes and forms can, and will, have a significant positive impact on diversity and excellence in academia.

Conclusions

This study is a real step forward to close the huge data gap that exists regarding menstruation and its impact on lifelong health. As with all good research studies, it throws up many questions and areas of further study. It is imperative that we delineate how the menstrual cycle may affect, predict or be impacted by other diseases. Use of FIGOs standardised terminology and classification system will facilitate such research. After all, menstruation affects over 50% of the population and its relative invisibility in current scientific literature needs to be addressed. It is time to obtain good data on women and their menstrual cycles to improve their health across the lifespan.