Pregnancy weight gain tied to rise in breast ca risk: those who gained more than 35 pounds increased their cancer risk by 40%. (Moderate Additional Risk).

SAN FRANCISCO -- Excessive weight gain during pregnancy may increase the risk of postmenopausal breast cancer, results of a retrospective study of Finnish women suggest.

Women who gained as little as 3 pounds above the recommended maximum of 35 pounds had a 40% increase in postmenopausal breast cancer risk compared with women who gained 25-30 pounds while pregnant, Dr. Leena Hilakivi-Clarke said at the annual meeting of the American Association for Cancer Research.

These findings offer another reason for women who are pregnant with singletons to gain the 25-35 pounds recommended by the American College of Obstetricians and Gynecologists, she said.

Although the relative risk of breast cancer increased significantly, the absolute increase in risk associated with excess weight gain was no greater than that associated with postmenopausal obesity or other known risk factors, none of which have more than a modest effect on raising the incidence of breast cancer, said Dr. HilakiviClarke of the Lombardi Cancer Center at Georgetown University, Washington.

High levels of estrogen associated with greater weight gain could be responsible for the increase in breast cancer risk, she said.