Risk of Breast Cancer in Relation to Infants’ and Mothers’ Birth Weights.

*Presented are three associations between the risk of breast cancer and the birth weights (top quintile vs. lower quintiles) of: the infant1, the mother2 and both3 birth weights.**Hazard ratios were adjusted for propensity score accounting for: age, age at menarche, age at the birth of the first child, age at menopause, maternal history of breast cancer, parity, body-mass index, race/ethnicity, diabetes and use of hormone replacement therapy. All covariates were measured or reported at the entry into the study. The adjusted analyses were carried out on data with missing covariates values for mother’s own birth weight and propensity score imputed using multiple imputation.The analyses of proportional hazard assumption were performed for all comparisons presented in subsets of subjects without missing data. All proportional hazard assumption tests showed no evidence of a significant non-proportional hazard (p>0.05, for all).