How does pregnancy reduce breast cancer risk?

Being pregnant while young is known to protect a women against breast cancer. But why? Research in BioMed Central’s open access journal Breast Cancer Research finds that Wnt/Notch signalling ratio is decreased in the breast tissue of mice which have given birth, compared to virgin mice of the same age.

Fuente : http://www.eurekalert.org/pub_releases/2013-04/bc-…