Crandall CJ, Liu J, Cauley J, Newcomb PA, Manson JE, Vitolins MZ, Jacobson LT, Rykman KK, Stefanick ML. Associations of Parity, Breastfeeding, and Fractures in the Women's Health Observational Study. Obstet Gynecol. 2017 07; 130(1):171-180.