[Reproductive function of women and risk of the development of breast cancer].

The relationship between risk for breast cancer and certain factors of reproductive function was studied on a "case-control" basis. It was demonstrated that the traditional and well-known index of age at first birth cannot be considered a universal factor for all females who have borne different numbers of children. Indexes which take into account age at all births proved more reliable in evaluating risk of cancer in bi-, tri- and multiparae. Indexes of relative risk and the role of characteristics of reproductive function are discussed.