Most women begin their menstrual cycles at around the age of 13. A new study suggested that those who start menstruating a few years before or after that average appear to be at increased risk of heart disease and stroke.
The study by researchers at Oxford University in Britain analyzed data collected from 1.3 million mostly white women - ages 50 to 64. They noticed a pattern among women who had their first menstrual cycle at age ten or younger, or 17 or older.
During the more than 10 years the women were followed, those two groups had a 27 percent increased risk of hospitalizations or death due to heart disease. There were 16 percent more hospitalizations or deaths from stroke among those groups, and high blood pressure led to a 20 percent increased likelihood of hospitalizations or related deaths.
Dexter Canoy , the study's lead author, is a cardiovascular epidemiologist at the University of Oxford's Cancer Epidemiology Unit within the Department of Population Health.
He said there is a strong association between the age of menarche, when a woman's first period occurs, and heart disease and stroke risk.
If plotted on a chart, he says it would look like the letter U, with the highest risk of cardiovascular disease among those who started menstruating at a very young age at one tip of the U, and those who began later on in their teens at the other.
Women who begin menstruating around age 13, which is typical, were seen to be at the lowest risk, according to Canoy, at the bottom of the U.
"Whether or not you are lean, overweight or obese, we found the same U-shape association, even if we take into account, let's say, you are taking medications for high blood pressure, or high cholesterol or have diabetes. It seems the association is robust," he said.
Canoy does see a link between menarche and weight. Obese girls tend to start menstruating at a younger age. They also often become obese adults, which is a risk factor for cardiovascular disease.
Canoy says it may be possible to lower the risk of heart disease and stroke in women by fighting obesity in children, which might also increase the age at which girls start to menstruate.
"Children who are obese can develop heart disease in the long run. But one aspect that can potentially be prevented is through the mechanism that might involve early-onset of menstruation."
Canoy says late-onset menstruation has historically been linked to malnutrition.
An article on the link between age of menarche and cardiovascular disease is published in the American Heart Association journal Circulation.