Objective: Lifestyle and gynecological history appear to influence bone mineral metabolism. There are conflicting data on the possible effects of breastfeeding on the subsequent development of densitometric osteoporosis or the development of fragility fractures. The objective of this study was to assess these effects. Material and methods: Observational, cross-sectional, open study, carried out in 758 postmenopausal women who were classified into two groups, depending on whether they had breastfed their children or not. Data were collected on lifestyles, gynecological history and fragility fractures. They underwent a general analysis, with renal and hepatic function, lipids, ions, as well as biochemical markers of bone remodeling, parathyroid hormone (PTH) and vitamin D (25HCC). Bone mineral density (BMD) was determined in the lumbar spine and in the proximal extremity of the femur by dual Xray absorptiometry (DXA). Likewise, a quantitative ultrasound (QUS) measurement was performed on the calcaneus of the dominant foot. The raw data, after being compared by groups, were adjusted by applying the propensity score matching method, making a more precise comparison of the variables studied. Results:The results prior to the application of the propensity score were adjusted for age and body mass index (BMI), since in the baseline study there were significant differences in these variables between both groups (prevalence of hip fractures and kyphosis and in the following biochemical parameters: specifically uric acid, glucose, HDL-cholesterol, triglycerides and phosphorus). These differences disappeared after adjusting for the variables that were included in the model by the applied linear logistic regression. After adjusting with the propensity score matching and with the finally obtained linear regression model, no influence of breastfeeding was obtained on bone mineral density, on the prevalence of densitometric osteoporosis or on the appearance of fragility fractures after menopause. Conclusion: Breastfeeding is not associated with higher or lower bone mineral density values, the prevalence of densitometric osteoporosis, or the presence of fragility fractures.