Table 2.

Recent large studies investigating the impact of pregnancy and breastfeeding on the risk of developing breast cancer according to biology

	Population	Number	Impact of parity on breast cancer risk according to subtype	Impact of breastfeeding on breast cancer risk according to subtype
Shinde et al. 2010 [38]	MD Anderson	2,473	Increase TNBC risk	Reduce TNBC risk
Palmer et al. 2011 [39]	African American	457	Reduce ER + BC risk	Reduce TNBC risk
Redondo et al. 2012 [40]	Spanish	501		Reduce TNBC risk
Chung et al. 2013 [41]	Korean	6,952	Reduce ER + BC risk
Li et al. 2013 [42]	American	1,962 (<45 years)	Reduce ER + BC risk	Reduce TNBC risk

BC, breast cancer; ER+, estrogen receptor-positive; TNBC, triple-negative breast cancer.