May 23, 2024—Having persistently irregular menstrual cycles appears to put women at heightened risk for cardiometabolic conditions including heart attack, hypertension, stroke, and diabetes, according to a large study from the Apple Women’s Health Study (AWHS).
The study was aimed at uncovering evidence about the connection between polycystic ovary syndrome (PCOS)—a common hormonal disorder—irregular cycles, and cardiometabolic risk. But researchers found that even women without PCOS—those with an irregular menstrual cycle, whose periods took more than five years to become regular, or who used hormones to establish a regular cycle—faced higher risk.
The study, published May 3 in JAMA Network Open, was conducted by researchers at the three institutions partnering to advance women’s health through the AWHS: Harvard T.H. Chan School of Public Health, the National Institute of Environmental Health Sciences, and Apple. The study was led by Harvard Chan School’s Zifan Wang, postdoctoral research fellow in the Department of Environmental Health, and Shruthi Mahalingaiah, co-principal investigator of the AWHS and assistant professor of environmental, reproductive, and women’s health.
Prior studies have found links between irregular menstrual cycles and cardiometabolic conditions, but findings around PCOS’ impact on this association have been limited. To address this gap, the researchers examined the self-reported menstrual patterns and cardiometabolic conditions of 60,789 women who enrolled in AWHS from November 2019 to December 2022. Among these participants, 12.3% reported being diagnosed with PCOS and 26.3% reported a prolonged time to menstrual regularity—meaning it took more than five years from their first period to establish a regular menstrual cycle. A smaller subset of participants (25,399) provided data on their current menstrual cycles; 25.6% of them reported their cycles to be irregular.
The study found links between menstrual cycle irregularity, with or without PCOS, and a variety of cardiometabolic conditions. PCOS was associated with all metabolic conditions examined in the study, including obesity and types 1 and 2 diabetes, as well as several cardiovascular conditions, including arrythmia, coronary artery disease, heart attack, and stroke. Among participants without PCOS, menstrual cycle irregularity was associated with high cholesterol, while prolonged time to cycle regularity was associated with hypertension; both groups faced higher prevalence of type 2 diabetes, arrythmia, and transient ischemic attack.
In a May 15 Healio article about the study, Mahalingaiah said the findings suggest that discussions of menstrual health need to move beyond the confines of OB/GYN offices.
“This research shows menses is a very important vital sign for half the population. There are major cardiometabolic implications,” she said. “The goal is to be sensitive to the menstrual cycle…and discuss very basic risk reduction options, which need to be individualized. Clinically, we also need to understand and treat what might be contributing to women’s irregular cycles.”
Read the study: Irregular Cycles, Ovulatory Disorders, and Cardiometabolic Conditions in a US-Based Digital Cohort
Read the Healio article: Apple data: Irregular menstrual cycles may predict cardiometabolic risk
Image: iStock/Nataliia Nesterenko