Women who started having menstrual periods before the age of 12 may have a higher risk of developing or dying of heart disease than other women, a new study suggests.

British researchers found that among nearly 16,000 middle-aged and older women followed for more than a decade, those who’d started menstruating before age 12 were 23 percent more likely to develop heart disease and 28 percent more likely to die of cardiovascular causes like heart attack or stroke.

These women also had a 22 percent higher overall death rate and a 25 percent higher risk of dying from cancer, according to findings published in the Journal of Clinical Endocrinology and Metabolism.

The results suggest that, across a wide population, women who began menstruating earlier have higher rates of certain health problems - and not that the risks are great for any one woman.

But they do suggest that women should be aware of the connection, and that it seems to be partly related to greater amounts of body fat in women who started menstruating early, according to Dr. Rajalakshmi Lakshman and colleagues at Cambridge University.

“These women may need greater awareness of their disease risks and weight control,” Lakshman told Reuters Health in an email.

She added that, “One key related message, therefore, is that tackling overweight early on in the next generation may be important to avoid early menarche and also reduce long-term disease risks.”

Previous studies have found evidence that early menarche (the term for a woman’s first menstrual period) can affect health later in life.

A large study of Norwegian women, for instance, found that those who began menstruating before age 12 were slightly more likely to die during the 37-year study period than their peers who’d begun menstruating at age 14.

Another study linked earlier menarche to a higher risk of diabetes in adulthood - a connection that appeared to be explained by higher body mass index (BMI) among women who’d begun menstruating earlier.

In this study, though, higher BMI only partly accounted for the relationship between early menstruation and higher cardiovascular risks and death rates.

“Other than increased body fat, we don’t yet know what other factors are involved,” Lakshman said.

The current study included 15,807 women between the ages of 40 and 79 who were followed for up to 13 years. During that time, 3,888 developed cardiovascular disease, including heart disease or stroke; 1,903 women died, including 640 from cardiovascular causes and 782 from cancer.

Early menarche remained linked to higher risks of coronary heart disease and deaths from cardiovascular disease and cancer after the researchers accounted for a number of other factors - such as age, BMI, smoking, exercise habits and education.

A number of studies have linked early menarche to an increased risk of breast cancer - possibly due to greater lifetime exposure to estrogen. It’s likely, according to Lakshman’s team, that this contributed to the higher cancer death rate in this study.

Women with an early menarche also had higher rates of cardiovascular disease risk factors, like high blood pressure and High cholesterol - but the reasons for that are unknown.

More research, according to Lakshman’s team, is needed to see whether early menarche, per se, is a risk factor for later-life diseases, or whether it is serving as a marker of other risk factors, like childhood obesity.

One “intriguing possibility,” Lakshman noted, is that excess weight in adolescence helps “program” later disease risks in some women, even if they lose weight in adulthood.

SOURCE: Journal of Clinical Endocrinology and Metabolism, December 2009.