It’s no surprise that the menstrual cycle can reveal important information about a woman’s reproductive health, but when we talk about the menstrual cycle being a vital sign, we mean that it can provide valuable information about whole-body health. A recent analysis of data collected over the past twenty years on women’s menstrual cycles reveals that having long and/or irregular cycles could mean you need to have a heart-to-heart with your doctor about your risk for cardiovascular disease [1].
Large study finds connection between irregular cycles and risk for future heart disease
An observational study, published in 2022, followed 80,630 registered nurses in the United States over twenty-four years and asked them to report on their cycle lengths, body mass index (BMI), and their experiences with cardiovascular disease (CVD). While the average age of the study participants was 37.7 years, the participants also provided information on their past cycle length and regularity, specifically from when they were ages 14-17, 18-22, and 29-46 years old, in order to make comparisons for different stages in life. During the study, 2.3% of participants experienced a cardiovascular disease event (such as coronary heart disease or stroke—yep, stroke is considered a cardiovascular disease even though it occurs in your brain, because ‘cardiovascular’ refers to both the heart and the blood vessels). The study found that irregular and long cycles were associated with a greater risk for developing cardiovascular disease, even when other known CVD risk factors like high cholesterol, high blood pressure, and type 2 diabetes were controlled for.
What qualifies as an “irregular” period or a “long” period?
In this study, “cycle regularity was categorized as very regular (no more than 3 to 4 days before or after expected), regular (within 5 to 7 days), usually irregular, always irregular, or no periods” ” though having no periods is actually amenorrhea). Long cycles were defined as lasting 32 days or more, though, interestingly, restorative reproductive medicine protocols like those used by FEMM and NaPro define a ‘long cycle’ as lasting more than 36 days. Very long cycles were defined as 40 days long or too irregular to estimate.
Study results
Compared to women with regular cycles, women with irregular cycles or no cycles in early adulthood had a 36% higher risk of developing cardiovascular disease, and women with irregular cycles in mid-adulthood had 40% higher risk. For women who experienced cycles lasting 40 days or longer in early adulthood (compared to women with shorter cycles), the risk of developing CVD was 44% higher in women who were 18-22 years old at the time of their cycle irregularity, and 30% higher in women who were 29 to 46 years old when they experienced irregular cycles. Heart disease (but not stroke) risk was highest when women fell into both categories, having both irregular and long cycles.
Several interesting correlations were uncovered when analyzing cycle characteristics in relation to cardiovascular disease:
- Women with irregular cycles were more likely to have higher BMI and high cholesterol
- While weight and cycle irregularity seemed to have an additive effect in CVD risk, smoking, diet, and physical activity seemed to contribute to risk independently of cycle irregularities
- The trend between irregular cycles and CVD was stronger in early and mid-adulthood than during the teen years, likely because cycles normally take some time to become regular when a teen first starts having periods. (Although, teen cycle issues like pain and bleeding that interfere with everyday life should still be taken seriously).
- CVD risk was elevated for women who had persistent irregular or long cycles throughout adulthood, as well as for women who had regular cycles earlier in life but whose cycles became irregular later on
- The authors of the study did various analyses to control for different variables, but the association between CVD and irregular and long cycles persisted
Study limitations
It is important to note that the majority of study participants were non-Hispanic White, and race was not a factor that was analyzed in this study, though black women, for instance, are significantly more likely to have CVD than white women. The authors also acknowledge that since participants were asked to retroactively report on cycle characteristics, some of the information could have been misremembered or inaccurate and these women may have been miscategorized in the study. Furthermore, women who had a CVD event before the start of the study were excluded, so the effect of irregular cycles on CVD could potentially be underestimated. However, the large number of participants does suggest that these results can be generalized to other women with irregular cycles [1].
Why does there seem to be a connection between irregular menstrual cycles and heart health?
We know that the hormones produced and regulated by the reproductive system have an array of effects on many other body systems. Estrogen is generally considered to have a protective effect against heart disease, which is why pre-menopausal women are at a lower risk for heart attacks than men. Because estrogen is produced by a follicle preparing for ovulation, having fewer cycles a year than the average woman means that the body is being exposed to estrogen, and its positive effects, less frequently.
The study also noted that the vast majority of women with irregular cycles have evidence of polycystic ovary syndrome (PCOS), and symptoms associated with PCOS, including lipid imbalance, type 2 diabetes, and issues with the arteries or veins, are known risk factors of CVD. This may help explain the association between cycle irregularity and cardiovascular health risk. There also seems to be a link between irregular cycles and having too-high insulin levels, which are also associated with CVD.
How can this information help women?
It’s important for women (including young women past their first few years of expected irregular teenage cycles) to understand that having irregular cycles is an indicator that all is not well somewhere within the body, especially in those who previously had regular cycles. This latest research suggests that irregular cycles may be a particular marker for risk of developing cardiovascular disease down the road. Knowing this, women can strive for improved heart health.
The Mayo Clinic lists several ways to get heart-healthy: quit smoking, exercise daily, limit salt, sugar, and saturated fat, maintain a healthy weight, sleep well, and manage stress. However, the important takeaway from the study linking irregular and/or long cycles and CVD is that heart health and cycle irregularities remained linked even when accounting for factors like smoking, exercise, and diet. This suggests that women may need to evaluate their heart health on two fronts: lifestyle habits and hormonal health.
How might improving hormonal health fix your irregular cycles and decrease cardiovascular risk?
In many ways, this is good news–it means you can improve your reproductive health and cardiovascular health at the same time! Many women wonder if their irregular cycles would make it impossible for them to chart their cycles, but this is absolutely not the case! Evidence-based methods of fertility awareness (not the rhythm method!) track specific signs such as cervical mucus, basal body temperature, and LH and estrogen levels, depending on the method being used, and does not rely on the number of days of your last cycle.
Different methods have different considerations and benefits, and finding an instructor is an important first step for learning a method that works for you in your unique circumstances. For women with irregular cycles, a method like Creighton may be especially helpful as it has a comprehensive mucus classification system, and Creighton boasts specially trained NaProTechnology providers who will work with you to treat reproductive issues (and for those interested in or using FEMM, medical protocols also exist for addressing cycle issues). Health practitioners trained in restorative reproductive medicine can suggest changes in diet and medications to treat hormonal imbalance and improve overall health.
According to the CDC, nearly half of American women live with some form of heart disease, and nearly 20% of female deaths are caused by heart disease. While there are numerous risk factors for developing heart disease, getting help for menstrual cycle irregularities can be important for improving both heart health and reproductive health.
This article was last updated on June 6th, 2023.
References:
- Wang Y, Stuart JJ, Rich-Edwards JW, et al. Menstrual Cycle Regularity and Length Across the Reproductive Lifespan and Risk of Cardiovascular Disease. JAMA Netw Open. 2022;5(10):e2238513. doi:10.1001/jamanetworkopen.2022.38513
Additional Reading:
Reasons Women Need Periods: The role of the menstrual cycle in heart health
The surprising health benefits of pregnancy
What are the long term effects of not having a period, and how can you fix amenorrhea?
