The objective of this study was to describe the trend of bone biomarkers in adults and adolescents women at 15, 90, 180 and 365 postpartum days (ppd) and its relation with bone mineral density (BMD). It was a prospective cohort of 32 teenager's ≤17 and 41 women from 18 to 29 years old. We evaluated diet, anthropometry, BMD, bone biomarkers and hormonal profile. In all, the concentration of N-telopeptide was higher at 15 days postpartum decreasing during first year postpartum, but adolescents had the highest concentration. The lowest N-telopeptide concentration was associated with highest increasing of the BMD. Osteocalcin concentration was lower in adolescents than in adults women (5 ± 3 vs 13 ± 4 ng/mL, p<0.001) during first year postpartum. Exclusive breastfeeding did not affect the BMD (p>0.050) or bone biomarkers. Osteocalcin concentration was positively associated with bone BMD (p<0.040), breastfeeding did not affect osteocalcin concentrations. Prolactin was higher among women who breastfed exclusively (p<0.001). Age and breastfeeding inversely correlated with bone biomarkers (p<0.001) N-telopeptide and PTHi respectively. We concluded that a lower N-telopeptide concentration and a higher osteocalcin concentration were associated with a higher increasing of BMD, so then, adolescents showed the lowest recovery of the BMD. Breastfeeding does not affect the BMD.