Blaauw, R. et al. «Risk factors for development of osteoporosis in a South African population.» (notmilk.com)
Actually, evidence suggests that breastfeeding may protect the woman against the development of osteoporosis even if she does not take extra calcium. (childbirthsolutions.com)
«Failure to obtain adequate bone mass by early adulthood may result in an increased fracture risk or even the development of osteoporosis later in adulthood.» (sciencedaily.com)