Cardiovascular disease (CVD) remains the leading cause of death and disease for women worldwide. In Western countries, approximately 45% of women aged over 20 years are affected by CVD, and it accounts for one-third of all female deaths. Recognising the unique sex-specific aspects in preventing CVD is crucial as historically, studies in cardiovascular disease have frequently focused on men. Recently, there has been growing interest in studying menstrual cycle characteristics and their potential impact on cardiovascular health. 

Regular menstrual cycles are a vital sign of women’s overall health, signalling normal functioning of the hypothalamic-pituitary-ovarian axis. However, about 20% of women of reproductive age experience irregular and long menstrual cycles due to endocrine disorders that disrupt this axis. These menstrual irregularities have been linked to several health conditions, including insulin resistance, metabolic disturbances, hyperandrogenism, and chronic inflammation. Consequently, they have been associated with an increased risk of coronary heart disease and related mortality, obesity, and type 2 diabetes.

To gain further insights into the connection between menstrual cycles and CVD, researchers conducted a large population-based cohort study using data from the UK Biobank. This study included over 58,000 women aged 40 to 69 years who had no pre-existing cardiovascular disease at the study’s outset. Participants were asked to report their current menstrual cycle length and regularity. The researchers followed these women for a median duration of 11.8 years, tracking the development of incident CVD cases through national health records and follow-up visits.

The study revealed some compelling associations between menstrual cycle characteristics and cardiovascular health. Here are the key findings:

• Women with irregular menstrual cycles were found to have a 19% higher risk of CVD events, including heart disease and atrial fibrillation, compared to those with regular menstrual cycles.

• Short (≤21 days) menstrual cycles were associated with a 29% higher risk of CVD events, while long (≥35 days) menstrual cycles showed an 11% increased risk. Specifically, short cycles were linked to a greater risk of coronary heart disease and myocardial infarction.

• Both short and long menstrual cycles were associated with a higher risk of atrial fibrillation.

• Interestingly, there was a significant interaction between irregular menstrual cycles and lower high-density lipoprotein cholesterol levels and smoking status, suggesting that these factors might influence CVD risk.

This study adds to the growing body of evidence suggesting that menstrual cycle characteristics throughout a woman’s reproductive lifespan could be associated with cardiovascular disease. Although the findings are significant, more research is needed to fully understand the underlying mechanisms and establish causality. Future studies are crucial to fill the remaining knowledge gaps and determine on how menstrual cycles might be prospectively linked to cardiovascular disease and subsequent events.

As we strive to ensure that women’s heart health is finally given the prominent status it deserves, understanding the potential impact of menstrual cycle characteristics on cardiovascular health becomes increasingly vital. The findings from the UK Biobank study provide valuable insights into the associations between irregular, short, and long menstrual cycles and CVD risk in women. Armed with this knowledge, women can take proactive steps towards better cardiovascular health. Regular check-ups, maintaining a healthy lifestyle, and discussing any menstrual irregularities with healthcare professionals can go a long way in safeguarding against CVD. 

Dr Hugh Coyne
Coyne Medical