Do you have an irregular period? It could be an early warning sign of heart disease

Women with irregular menstrual periods appear to face a significantly higher risk of cardiovascular disease, a new study suggests.

Up to a fifth of American women of reproductive age – roughly 12 million of them – deal with an abnormal period that occurs when the length of one’s menstrual cycle unexpectedly falls outside of the regular range, typically fewer than 21 days or longer than 35 days.

Irregular menstrual periods can be an inconvenience for millions of women at best, but at worst, they increase women’s risk of heart disease by 19 percent and of atrial fibrillation by a staggering 40 percent, according to a team of researchers in China.

The study followed more than 58,000 women for 12 years, after which researchers found roughly 3.4 percent of the women with irregular cycles developed cardiovascular disease compared to about 2.5 percent of those with normal periods.

Dr Huijie Zhang, a professor at Southern Medical University in China and lead author of the study, said: ‘These findings have important public health implications for the prevention of atrial fibrillation and heart attack among women and highlight the importance of monitoring menstrual cycle characteristics throughout a woman’s reproductive life.’

An analysis of data for more than 58,000 women found that short (less than 21 days) as well as long (more than 35 days) menstrual cycles were associated with a higher risk of developing heart disease, atrial fibrillation, and heart attack 

The sweeping study reflected health data of more than 58,000 healthy women in the UK who reported on their cycle length at the start of a 12-year follow-up period. 

The menstrual cycle is counted from the first day of one period to the first day of the next. 

The study, published in the Journal of the American Heart Association, relied on extensive health data in the UK BioBank, a large-scale population health research initiative containing in-depth genetic and health information from half a million UK participants.

The average age of the participants, none of whom had cardiovascular disease at the start of the study, was 46.

After 11 years and eight months, researchers recorded 1,623 cardiovascular ‘events’ among the participants, including 827 incident cases of coronary heart disease, 199 heart attacks, 271 strokes, 174 cases of heart failure, and 393 cases of atrial fibrillation, or irregular heartbeat that can lead to blood clots.

Over 1.7 percent of women with irregular cycles developed coronary heart disease (CHD), a result of plaque buildup on the walls of the arteries that then restricts the flow of oxygen-rich blood to the heart. 

But just 1.3 percent of women with regular periods developed CHD.

And about 0.6 percent of those with regular cycles developed atrial fibrillation, compared with nearly one percent of those with irregular cycles.

The connection between irregular menstrual cycles and heart disease is not completely clear, though previous research has found that they are strongly linked with various heart disease risk factors including high cholesterol, hypertension, and polycystic ovarian syndrome.

Hormone fluctuations that are fundamental to the menstrual cycle also influence cardiovascular function. Estrogen, which dips after ovulation but then gradually rises, has protective effects on the heart.

Estrogen helps tissues and blood vessels stay supple and flexible, aiding in healthy blood flow, keeping blood pressure low, increasing HD (good) cholesterol, and absorbing damaging free radicals.

While irregular cycles are common, they are not healthy and in fact reflect a poorly-functioning hypothalamic‐pituitary‐ovarian axis, the tightly regulated network of systems that control female reproduction. 

Dr Zhang said: ‘The association between menstrual cycle characteristics and adverse cardiovascular outcomes remains unclear. 

‘Considering the increasing prevalence of heart disease — with 45 percent of women in Western countries affected — and related mortality, there is a need to explore these risk factors.’