Placenta consists a temporary but highly active organ that plays a central role in fetal development and helps regulate the hormonal environment during pregnancy. In recent years, researchers have become increasingly interested in whether placental weight may be linked to breast cancer risk in both mothers and their children. 
Placental weight is often considered an indirect indicator of placental function and efficiency, and several studies suggest that unusually high placental weight may reflect increased exposure to hormones and growth factors associated with breast cancer development.
This review examines current evidence on the relationship between placental weight and breast cancer risk, focusing on possible hormonal, epigenetic, and inflammatory mechanisms. 
Higher placental weight has been associated with elevated levels of estrogen and insulin-like growth factor 1 (IGF-1), both of which are known to influence mammary gland development and carcinogenesis. 
Findings from cohort and case-control studies are discussed together with the biological mechanisms that may explain these associations. Finally, the review considers the possible clinical implications of these findings and highlights directions for future research.