- Researchers link women's body fat to reproductive factors such as age of puberty
- It's not clear whether the heart disease link is associated with childhood obesity
- Research may help identify women who are vulnerable to heart risks
Predicting heart disease risk is not an exact science, but doctors are building the case for another tool to guide their evaluations when it comes to women.
Women tend to develop heart disease later in life than men, which makes the familiar risk factors -- high cholesterol, high blood pressure, and overweight or obesity -- useful, but not entirely reliable predictors of heart trouble.
So researchers involved in the decades-long Framingham Heart Study, one of the most extensive investigations of heart disease risk factors that began in 1948, decided to look at reproductive factors that may refine doctors' ability to help women learn how vulnerable they are to the disease.
Experts currently believe that women may not experience heart problems until nearly a decade on average after men because of the female hormone estrogen, which shields the heart until menopause, around ages 50 to 60, after which its levels drop dramatically.
That's why the Framingham researchers focused on 1,638 female children and third generation participants of the original study members, all over age 40, to see if reproductive factors could be correlated to body weight, and in turn, heart disease risk.
They recorded factors such as the age at which a woman began menstruating, the number of children she had, and her age at menopause and connected them to obesity-related measures such as fat distribution in the body and types of fat (visceral fat in the belly area versus less metabolically active subcutaneous fat found underneath the skin).
"Understanding whether body fat distribution is associated with female reproductive factors may provide insight into the potential mechanisms linking them to (heart disease) and its risk factors," the authors write.
After adjusting for factors such as age, smoking, alcohol use, physical activity, hormone replacement therapy and menopausal status, all of which can influence body weight and heart disease risk, the authors found that earlier menses was linked to higher body mass index (BMI) and greater waist circumference (or denser fat deposits around the belly).
The results, accepted for publication in The Endocrine Society's Journal of Clinical Endocrinology & Metabolism, support earlier studies that found menstruating before age 12 may contribute to a 23% greater risk of developing heart disease and a 28% higher risk of dying from heart attack or stroke.
Unlike other analyses, however, the current study did not find that age at menopause, or the number of children a woman had, affected her BMI or fat distribution; researchers had believed that overweight or obesity contributed to early menopause and an elevated risk of heart disease.
The authors admit that teasing apart the relationship between reproductive factors and obesity is challenging; emerging data suggests, for example, that childhood obesity and a greater volume of fat tissue may trigger early menses, but it's not clear whether the link between early menses and heart disease risk found in the current study is actually the result of childhood obesity tracking into adulthood, and not related to early puberty.
Either way, the growing body of knowledge around women's heart disease may help to better identify those who are particularly vulnerable.
And based on the latest data, it may be worth studying whether doctors should begin discussing weight issues and heart disease risk factors with girls who get their periods early, in an effort to protect them from later heart disease.