tingfeng 说的不错，专家已经有文章谈论过

Can breastfeeding lower breast cancer risk?

http://www.cancer.org/cancer/news/expertvoices/post/2013/05/07/can-breastfeeding-lower-breast-cancer-risk.aspx

Pregnancy and Breast Cancer

http://www.cancer.org/cancer/breastcancer/moreinformation/pregnancy-and-breast-cancer