Women with menstrual cycle dysfunction may experience adverse cardiovascular health consequences

A study of more than 58,000 women over a 12-year period found that longer or shorter menstrual cycles were associated with a higher risk of developing cardiovascular disease, heart attack or atrial fibrillation (AFib), according to new research published today in the Journal of the American Heart Association, an open access, peer-reviewed journal of the American Heart Association.

Regular menstrual cycle length, defined as cycle length between 22 and 34 days, throughout a woman's reproductive life reflects normal functioning of the connected hormone systems among the hypothalamus, pituitary gland and ovaries and are a vital indicator of overall health. Irregular menstrual cycles are a common endocrine disorder, with about 20% of women experiencing long cycles or cycles of varying lengths, according to previous research.

Previous research has found that irregular menstrual cycles are significantly related to multiple heart disease risk factors, including insulin resistance, high cholesterol, high blood pressure, chronic inflammation and polycystic ovarian syndrome. Other studies have found that women are at higher risk for arrhythmias, or irregular heartbeats, due to hormonal fluctuations of the menstrual cycle.

The association between menstrual cycle characteristics and adverse cardiovascular outcomes remains unclear. Considering the increasing prevalence of heart disease -; with 45% of women in Western countries affected -; and related mortality, there is a need to explore these risk factors."

Huijie Zhang, M.D., Ph.D., senior author, chief physician and professor at Nanfang Hospital of Southern Medical University in China

Researchers analyzed data from the U.K. Biobank to investigate whether menstrual cycle length, which was self-reported, was associated with overall heart disease and specific cardiovascular events in women. The U.K. Biobank is a large database of health information for more than 500,000 adults – enrolled from 2006 until 2010 – who receive care through the United Kingdom's National Health Service. This study included health data for 58,056 women with an average age of 46 years at the beginning of the study period, as well as no cardiovascular disease. Health data was collected through four follow-up visits that took place from 2006-2010, 2012-2013, and in 2014 and 2019. Participants with menopause when the study began were excluded. The end of the study period was November 30, 2020, the most recent date for health data available for this analysis.

During a median follow-up period of 12 years, more than 1,600 cardiovascular events were noted among the participants, including coronary heart disease, heart attack, atrial fibrillation, stroke or heart failure. The analysis found:

• Menstrual cycles less than 21 days or longer than 35 days were associated with a 19% higher risk of heart disease among those women compared to the women with regular menstrual cycle length, defined by this study as between 22 to 34 days, as well as a 40% higher risk of atrial fibrillation.
• Shorter menstrual cycles were associated with a 29% higher risk of CVD events -; including coronary heart disease, heart attack, atrial fibrillation, stroke and heart failure -; and longer menstrual cycles were associated with an 11% higher risk of those CVD events, compared with regular-length menstrual cycles.
• Shorter menstrual cycles were associated with a 38% higher risk of atrial fibrillation, and longer menstrual cycles were associated with a 30% higher risk atrial fibrillation, compared with regular length menstrual cycles.
• Menstrual cycle length was not associated with an increased risk of stroke or heart failure.

These increased risks of cardiovascular disease were observed in the women independent of other risk factors, including age, ethnicity, BMI or body mass index, smoking status, drinking status, physical activity, baseline cholesterol levels, history of high blood pressure or Type 2 diabetes, history of oral contraceptive use or hormone replacement therapy, and family history of heart disease or stroke.

"Our analysis indicates that women with menstrual cycle dysfunction may experience adverse cardiovascular health consequences, therefore, we need to raise awareness that individuals with irregular menstrual cycle patterns may be more likely to develop heart disease," Zhang said. "These findings have important public health implications for the prevention of atrial fibrillation and heart attack among women and highlight the importance of monitoring menstrual cycle characteristics throughout a woman's reproductive life."

The study had several limitations including that its question about menstrual regularity relied on the participant's interpretation of irregular menstrual cycle length. The researchers could not rule out the potential impact of menopausal transition on irregular menstrual cycles because participant data at younger ages and including hormone levels were not available. Additionally, the U.K. Biobank dataset is a population of older adults (ages 40-69 years), the majority of whom self-identified as white, meaning the findings may not be generalizable to women from diverse racial or ethnic backgrounds or younger women.