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How does menstrual cycle length affect the risk of cardiovascular disease? Image credit: mrs/Getty Images.
  • Cardiovascular disease is the leading cause of death worldwide.
  • Women are at an increased risk for certain types of cardiovascular disease compared to men.
  • Researchers from Southern Medical University Nanfang Hospital have found that women with irregular menstrual cycles are at an increased risk for cardiovascular disease.

Cardiovascular disease is the leading cause of death in the world. In 2020, about 19.1 million people globally died from cardiovascular diseases or events, which include coronary artery disease, heart attack, heart failure, and atrial fibrillation.

Cardiovascular disease is also, more specifically, the leading cause of death for women worldwide.

A study earlier this year found that women are twice as likely to die from a heart attack than men. And a study published in 2022 found women are at a greater risk for developing atrial fibrillation than men if they are the same height and size.

Now, researchers from Southern Medical University Nanfang Hospital in Guangdong, China, say that women with irregular menstrual cycles are also at a higher risk for developing cardiovascular disease.

This study was recently published in the Journal of the American Heart Association.

In this study, Dr. Huijie Zhang, chief physician and professor in the Department of Endocrinology and Metabolism at Southern Medical University Nanfang Hospital, and her team analyzed data from more than 58,000 women from the U.K. Biobank.

Study participants had an average age of 46 years, no prior medical history of cardiovascular disease, and had self-reported menstrual cycle length information at the start of the study period.

During a median follow-up period of 12 years, researchers noted more than 1,600 cardiovascular events among the study participants.

Upon further analysis, the scientists found that participants with menstrual cycles of less than 21 days or longer than 35 days had a 19% higher risk of heart disease compared to women with regular menstrual cycles.

Participants with shorter-length menstrual cycles had a 29% increased risk of having a cardiovascular event, while those with longer-length menstrual cycles had an 11% higher risk.

The researchers also found that study participants with shorter-length menstrual cycles had a 38% higher risk of atrial fibrillation. Those with longer-length menstrual cycles had a 30% higher risk of atrial fibrillation.

“[Cardiovascular disease] is the leading cause of morbidity and mortality for women worldwide [and] the findings help us to raise awareness that having irregular menstrual cycle patterns may mean more heart disease,” Dr. Zhang told Medical News Today.

“Our study suggested that irregular menstrual cycles were significantly associated with a higher risk of atrial fibrillation, which might be a previously unknown risk factor for atrial fibrillation,” she added.

The researchers further noted that these increased cardiovascular disease risks were independent of other risk factors, including smoking, body mass index (BMI), cholesterol levels, and previous history of high blood pressure or type 2 diabetes.

After reviewing this study, Dr. Nicole Weinberg, a cardiologist at Providence Saint John’s Health Center in Santa Monica, CA, not involved in the research, told MNT she found this study to be both provocative and interesting.

“A lot of the overlap between gynecology and cardiology has a lot to do with pregnancy, [with] how women fare with getting pregnant — gestational diabetes, pregnancy-induced hypertension, and preeclampsia,” she explained.

“But this study takes it a step earlier to say, ‘okay, forget about what happens when we’re trying to assess their vascular supply and all these different stressors on their cardiovascular system with pregnancy. Let’s look at it even before their body is under those stressors and see, are we getting windows into their cardiovascular health with their menstrual cycle?’”
— Dr. Nicole Weinberg

Dr. Weinberg said she would like to see these findings fleshed out a bit more to find specific risks for different types of cardiovascular disease.

“And then the pie in the sky would be going even earlier than that—are there certain things that are experienced before women start to menstruate, what are those things, and […] can any of those things be modified or examined even earlier to make sure that we put [women] on a healthier [life] path so that ultimately cardiovascular disease does not become their leading cause of death,” she added.

Each month, a woman’s body goes through a menstrual cycle featuring certain phases that allow the body to prepare for pregnancy.

A typical menstrual cycle includes:

  • menstruation where a woman has her period
  • follicular phase that starts at the same time as menstruation but runs a bit longer, where a new egg begins maturing
  • ovulation phase when the now-matured egg is released
  • luteal phase where the uterus prepares for a possibly fertilized egg.

The luteal phase is also where women may experience premenstrual syndrome (PMS).

On average, a healthy menstrual cycle lasts about 28 days and can vary between 25 to 30 days depending on the person.

An irregular menstrual cycle — medically known as oligomenorrhea — occurs if the cycle lasts for less than 24 days or more than 38 days.

Some causes of an irregular menstrual cycle include:

When a woman has an irregular menstrual cycle for a prolonged period of time, they may raise their risk for certain diseases, such as osteoporosis, iron deficiency anemia, and endometrial hyperplasia.

This is not the first study to have linked irregular menstrual cycles to a higher risk for cardiovascular disease. Previous research says women increase their cardiovascular disease risk as they move to postmenopause due to a reduced amount of estrogen in their bodies.

And a study in 2022 found women with an irregular menstrual cycle had a 20% increased risk of developing heart disease compared to women with a normal menstrual cycle.

“Women with menstrual cycle dysfunction may experience adverse cardiovascular health consequences,” Dr. Zhang, explained to MNT as to why she and her colleagues decided to study the correlation between menstrual cycle length and cardiovascular disease risk.

“However, whether the menstrual cycle is prospectively associated with cardiovascular disease and subsequent cardiovascular events is unknown,” she pointed out.

MNT also spoke with Dr. G. Thomas Ruiz, OB/GYN lead at MemorialCare Orange Coast Medical Center in Fountain Valley, California, who was not involved in the research, about this study.

He said these findings were not surprising because a main cause of irregular menstrual cycles is PCOS.

“That is a multi-pronged disorder where the patient has hyperinsulinemia [or] insulin insensitivity,” Dr. Ruiz explained.

“[Individuals with PCOS] will sometimes have elevated free testosterone levels. They’re at increased risk for type 2 adult-onset diabetes. And all of those disorders are associated with dyslipidemia and all complications associated with what you might see in a diabetic,” he noted.

Dr. Ruiz said most women do not realize how much of an impact an irregular menstrual cycle can have on their overall health, making it important for doctors to discuss it.

“You have to discuss it [with a doctor] because in most cases, it actually should be treated,” he continued. “If you have someone with irregular menses and they fit the profile of PCOS, they’re also at an increase for endometrial hyperplasia, which can be a premalignant lesion and increases your risk of endometrial cancer.”