Birth Weight as a Risk Factor for Breast Cancer: a Meta-Analysis of 18 Epidemiologic Studies

Background: Birth weight has been identified as a birth-related factor associated with the risk of breast cancer. However, the evidence is inconsistent. Methods: To investigate the association between birth weight and breast cancer, we conducted a metaanalysis of published studies between 1996 and 2008. Eighteen studies encompassing 16,424 breast cancer cases were included in the meta-analysis. Data were combined using a fixed-effect or random-effect model depending on the heterogeneity across studies. Results: Women with their own birth weight >4000 g or 8.5 lb had a higher risk for developing breast cancer than those with birth weight(OR1⁄41.20, 95% CI 1.08, 1.34). Findings were also consistent with a doseresponse pattern effect. The summary effect estimate for breast cancer risk per 1 kg increase in birth weight was statistically significant (random effects OR1⁄41.07, 95% CI 1.02, 1.12). Conclusions: Although these results provided no evidence indicating whether birth weight is more strongly related to early-onset than to later-onset breast cancer, our findings suggest an association between birth weight and breast cancer. The underlying biological mechanism relating to this phenomenon needs additional study. Disciplines Medicine and Health Sciences | Other Medicine and Health Sciences | Women's Health Authors Xiaohui Xu, Amy B. Dailey, Mary Peoples-Sheps, Evelyn O. Talbott, Ning Li, and Jeffrey Roth This article is available at The Cupola: Scholarship at Gettysburg College: http://cupola.gettysburg.edu/healthfac/18