Women who go through menopause later rather than sooner may have a somewhat longer life expectancy, a large study suggests.

Researchers found that among more than 12,000 Dutch women followed for 17 years, life expectancy crept up with each year menopause was delayed. At the extremes, women who went through menopause after age 55 lived 2 years longer, on average, compared with women who had their last menstrual cycle before age 40.

The gains in longevity were largely related to a lower risk of death from Heart disease and Stroke.

Since smoking seems to promote earlier menopause, the findings offer one more reason for women to give up the habit, according to study co-author Dr. Yvonne T. van der Schouw of University Medical Center Utrecht in The Netherlands.

“Smoking is one of the most important determinants of age at menopause,” she said, “and is, therefore, also the most important modifiable…factor.”

This “fits in well,” she added, with the general recommendation to avoid smoking to help prevent cardiovascular disease and cancer.

Other factors that may contribute to earlier menopause, van der Schouw noted, include a history of irregular menstrual cycles, having no children or only one, and having a long gap between a first and second birth. But these are influences, she pointed out, that may not be open to change.

The study, published in the journal Epidemiology, involved 12,134 postmenopausal women who completed questionnaires on their medical and reproductive histories and smoking habits, and were then followed for 17 years, on average.

More than three-quarters of the women went through menopause sometime between the ages of 45 and 54. On average, smokers had their last menstrual cycles about a year sooner than non-smokers - at age 48 versus 49.

Overall, the researchers found, for each year a woman’s menopause was delayed, her risk of death, adjusted for age, dipped by 2 percent. In particular, the risks of death from Heart disease and Stroke fell as age at menopause rose - even when accounting for age and factors such as smoking, body weight and high blood pressure.

On the other hand, later menopause was tied to a higher risk of dying from ovarian or uterine cancers. But because Heart disease and Stroke are far more common than those cancers, van der Schouw noted, the net effect was a longer life expectancy for women with a later menopause.

It’s known that before menopause, women generally have a lower risk of cardiovascular disease than men do, but the risk climbs substantially after menopause. This pattern is believed to reflect a protective effect of estrogen on the heart and blood vessels.

On the other hand, late menopause may raise the risk of ovarian or uterine cancer by increasing a woman’s lifetime exposure to estrogen, which may feed the growth of cancer cells.

SOURCE: Epidemiology, July 2005.