Reproductive history and risk of breast cancer: a case-control study in an unselected Swedish population.

Variables in reproductive histories were studied in 179 consecutively detected, unselected breast cancer patients and age-matched controls selected from a computerized population register. The comparison between patients and controls showed no significant difference in age at meanarche, age at first birth, age at menopause or number of children. A subdivision into pre- and post-menopausal women yielded no further information. These results are at variance with most earlier reports, possible because the controls here were selected from the whole female population instead of hospitalized patients. Our data do not support the view that it is possible to define groups at high risk for breast cancer on the basis of productive histories.