Effects of irregular menstrual cycles on cardiovascular health

According to a recent study published in the Journal of the American Heart Association, cardiovascular disease (CVD) risks are increased by long or short menstrual cycle length.

CVD impacts 45% of women in Western countries aged over 20 years, causing one-third of all deaths in women. This makes CVD the leading source of morbidity and mortality for women worldwide, with prevention efforts focused on sex-specific factors which increase CVD risk.

Women’s general health may be analyzed through the frequency of menstrual cycles, with regular menstrual cycles indicating improved health. Long and irregular menstrual cycles are observed in 20% of women and are associated with metabolic disturbances, insulin resistance, chronic inflammation, and hyperandrogenism, which are linked to increased risk of coronary heart disease.

There is currently limited data on the link between CVD and menstrual cycle frequency and length. To determine the association between these factors, investigators conducted a large population‐based cohort study using data from UK Biobank.

UK Biobank is a prospective cohort study based in the United Kingdom collecting data from over 500,000 individuals aged 40 to 69 years from 2006 to 2010. Information on sociodemographic data, medical history, medication use, and lifestyle factors of participants was gathered through a touch-screen questionnaire.

Participants also underwent a physical assessment including anthropomorphic data and vital sign measurements, with incident diagnoses developed during follow-up using follow-up visits and national health records. Menstrual cycle length and regularity was reported by participants at baseline.

Exclusion criteria included having reached menopause, having missing data on menopause, possibly being pregnant, and having a CVD diagnosis at baseline. After exclusion, 58,056 women were included in the final analysis.

Women reported menstrual cycle length at baseline, with irregular menstrual cycle define by self-report of irregular cycles, cycle length of 21 days or less, and cycle length of 35 days or more. A menstrual cycle length of 22 to 34 days was considered regular. Cycle length categories included 21 days or less, 22 to 27 days, 28 to 34 days, and 35 days or more.

CVD events such as heart failure, myocardial infarction, coronary heart disease, atrial fibrillation, and stroke were the primary outcome of the study. Data up to November 30, 2020, was available for analysis.

Links to Health Episode Statistics, the Patient Episode Database, and the Scottish Morbidity Records were consulted for hospital admission data. Mortality data was obtained from National Health Service Digital and the National Health Service Central Register.

Outcomes were defined using International Classification of Diseases, Tenth Revision (ICD‐10) codes. Covariates included age and body mass index (BMI) at baseline, education level, race and ethnicity, and individual history of hypertension, diabetes, depression, and severe stress determined through ICD-10 codes.

Women were aged a mean 46.1 years at baseline. Those with irregular cycles more often had a higher BMI and total cholesterol than those with regular cycles, along with being more likely to have histories of hypertension and diabetes or be current smokers. These women were also more likely to a family history of CVD and stroke.

Similar differences in characteristics were observed in women with short or long cycle length compared to regular cycle length. There were 1623 CVD events observed during follow-up, including 827 incident CVD events, 393 atrial fibrillations, 271 strokes, 199 myocardial infarctions, and 174 heart failure events.

CVD incidence was increased among women with irregular menstrual cycles, along with women who had menstrual cycle lengths of 21 days or less or 35 days or more. A significant link was found even after adjustments for covariates. Further significant associations were found in women with continued menstrual cycle irregularity during follow-up.

These results indicate a significant association with irregular menstrual cycles and short and long cycle length with increased CVD risk. Investigators stressed the importance of monitoring menstrual cycle characteristics throughout a woman’s reproductive life.

Reference:

Huang C, Lin B, Yuan Y, et al.Associations of menstrual cycle regularity and length with cardiovascular diseases: A prospective study from UK Biobank. Journal of the American Heart Association. 2023. doi:10.1161/JAHA.122.029020

This article was initially published by our sister publication, Contemporary OB/GYN®.