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Women with irregular or long menstrual cycles may be more likely to die prematurely when compared to those who have regular or short cycles, according to a study.
Participants who said they always had irregular periods were more likely to pass away before the age of 70, or prematurely, than those who had very regular cycles, the findings published in the journal The BMJ showed.
Irregular and long cycles in adulthood were linked to a higher risk of dying of cancer or cardiovascular disease, but the link was strongest for the latter.
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The team made similar findings in the death risk for women who had cycles lasting 40 days or more, or which were too irregular to estimate when compared with participants who had cycles between 26 to 31 days, which is considered normal.
The likelihood dying prematurely was strongest for those who had irregular and long menstrual cycles in their adolescence and as well as in adulthood.
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When compared to those with very regular cycles, those who had irregular periods or none were more likely to have a higher body mass index (BMI), a higher chance of having high blood pressure, high cholesterol, excessive hair, endometriosis, growths in the uterus, and a family history of diabetes.
The authors believe the risk of dying prematurely may be partly down to these women having disrupted hormones.
The study involved 79,505 women who had not reached menopause, and did not have a prior history of cardiovascular disease, cancer, or diabetes. On average, they were aged 37.7 years old when the study started in 1993. The participants were taking part in the ongoing Nurses’ Health Study II, and were asked questions about their lifestyles and medical history twice a year. They reported how long and regular their periods were at the ages of 14 to 17 years old, 18 to 22, and 29 to 46.
Women were said to have very regular periods if they started 3 to 4 days after it was expected, and regular within 5 to 7 days. The participants were also asked to report on the usual length of their menstrual cycles, or the days between the first bleeds of each cycle. The options were 21 days or less, 21 to 25 days, 26 to 31 days, 32 to 39 days, 40 to 50 days, more than 50 days, or too irregular to estimate.
The team followed up with the patients after 24 years by looking at medical records, autopsy reports or death certificates, finding 1,975 had died before the age of 70, including 894 from cancer, and 172 from cardiovascular disease.
Co-author Dr. Jorge E. Chavarro, associate professor in the Departments of Nutrition and Epidemiology at Harvard T.H. Chan School of Public Health, told Newsweek there is a lot of scientific literature on the relationship between problems with the menstrual cycle with the risk of major chronic diseases, but the impact on premature death was less clear.
The most important limitation of the study was that the authors assessed the patterns of the women’s cycles at three points in their lives, and asked them to remember their cycles in adolescence, he said. This may make the associations they observed weaker than they are in reality.
Chavarro hopes the study will raise awareness among primary care providers that a woman’s menstrual cycle may be a “vital sign” when evaluating her health. Women worried by the findings should contact their doctor, he said.
Experts not involved in the research said the findings were sound, but also pointed out the study’s limitations.
Dr. Frans M. Helmerhorst, a retired gynaecologist currently affiliated with the clinical epidemiology department at Leiden University Medical Center, the Netherlands, told Newsweek the study adds to previous research suggesting that irregular cycles, which suggest a woman is not releasing eggs, may be linked with cardiovascular disease and death due to obesity.
Dr. Jacqueline Maybin, senior research fellow and consultant gynaecologist at the MRC Centre for Reproductive Health at the U.K.’s University of Edinburgh, said in a statement the methods were “sound” but pointed out that the participants were nurses, some of whom would have likely worked very irregular hours. Shift work, particularly night shifts, has been shown to have a significant impact on long-term health, she said. Disrupting the body’s internal clock is also known to affect the regularity of periods. These factors were not accounted for the in analysis, and may limit whether the findings can be applied to the general public, according to Maybin.
She said it should be stressed the study found a link between irregular cycles and early death, but did not prove it causes early death. “The association may be due to chance,” she said.
“This study is a real step forward in closing the data gap that exists in women’s health. It raises many interesting research questions and areas of future study,” she said.
Adam Balen, Royal College of Obstetricians and Gynaecologists spokesperson on reproductive medicine and past chair of the British Fertility Society, said: “young women with irregular periods need a thorough assessment not only of their hormones and metabolism but also of their lifestyle so that they can be advised about steps that they can take which might enhance their overall health.”
Rachel Tribe, professor of maternal and perinatal sciences at King’s College London, U.K., said the findings were limited because the participants were mostly white, so may not relate to a wider population.