A protective effect from breastfeeding.
D001942:Breast Feeding; D001943:Breast Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D016022:Case-Control Studies; D003906:Developing Countries; D005260:Female; D006801:Humans; D015994:Incidence; D014481:United States / Q000453:epidemiology