Maternal Age and Birth Rank of Women With Breast Cancer2

Abstract

Data from a large international case-control study of breast cancer suggested that women born to young mothers had a 25% lower risk of breast cancer. The association was not secondary to a tendency for these women themselves to have had children at early ages. The data provided no indication of a meaningful association between breast cancer risk and birth rank. Confounding was controlled by stratification according to a summary confounder score.