Why Pregnancy Protects Against Breast Cancer

Breast tissues different in post-menopausal women

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Motherhood may be one of the greatest blessings for many women. First, a woman receives the precious gift of a child. Then, she also is protected from breast cancer throughout her life.

Discovering that women with children develop breast cancer less frequently than women without children will allow researchers to develop preventative measures to protect women who have not had children from the disease.

"Pregnancy may reduce risk of breast cancer."

Ricardo López de Cicco, PhD, a senior research associate at Fox Chase Cancer Center, says, "When a woman has multiple pregnancies beginning at a relatively young age, we see a protective effect against breast cancer."

He further explained, “we identified a post-pregnancy genomic signature [genes] that can still be seen even after menopause. That is very important because it could begin to help us understand why women who have children early benefit from a reduced risk of breast cancer throughout their lives."

The Study

Jose Russo, MD, director of the Breast Cancer Research Laboratory at Fox Chase, who led the new study and his team:

  • compared gene expression in breast tissue from 44 post-menopausal women who have children and 21 who did not.
  • validated the results an independent cohort of 61 post-menopausal women, 38 who had children and 23 who did not.
  • identified 208 genes that were differently expressed between the two groups. 
  • may help researchers begin to understand why women who have had children early in their childbearing years continue to benefit from a reduced risk of breast cancer 30, 40 even 50 years later 
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Review Date: 
April 5, 2011
Last Updated:
October 18, 2012