New mothers now have even more incentive to shed pounds gained during pregnancy, other than wanting to fit into those pre-pregnancy jeans. A new study indicates an association between gaining weight in adulthood and an increased risk of breast cancer after menopause.

“We did find some suggestion that weight gain during the 30s and 40s, weight gain since a woman’s first pregnancy and weight gain since menopause, especially for women with a longer time since menopause, may all be of importance in relation to postmenopausal breast cancer risk,” the researchers report in the International Journal of Cancer this month.

It is well established that being overweight is a risk factor for breast cancer. Mounting evidence indicates that weight gain in adult life is more predictive of breast cancer risk than absolute body weight, but little is known about the impact of the timing of weight gain in adult life in relation to breast cancer risk.

Dr. Daikwon Han of Morehead State University in Kentucky and colleagues looked at this issue in 1,166 women with breast cancer and 2,105 without.

Han’s team noted, among other things, a roughly 70 percent increased risk of breast cancer among postmenopausal women who gained more than 60 pounds between age 20 and menopause, compared with women who gained less than 20 pounds.

There was a 4 percent increase in breast cancer risk for each 11-pound increase in adult weight, the investigators report.

These results, Han and associates say, suggest that there are time periods of weight gain that have “greater impact” on breast cancer risk than others.

SOURCE: International Journal of Cancer, December 15, 2006.