TOPLINE:

A longer duration of breastfeeding (beyond 8 months) in premenopausal women was associated with improved maternal bone and muscle composition, showing greater reductions in vertebral bone marrow adiposity and muscle fat infiltration over 5 years with enhanced metabolic health, better insulin sensitivity, and lower insulin resistance.

METHODOLOGY:

• This retrospective longitudinal analysis included 37 premenopausal women (19 breastfeeding for more than 8 months and 18 breastfeeding for 8 months or less) between April 2013 and September 2015.
• MRI scans were performed at baseline (6-15 months postpartum) and at a follow-up of 5 years. Women in the group with a shorter duration of breastfeeding had completely stopped breastfeeding at baseline.
• Outcomes included changes in proton density fat fraction (PDFF) maps of the vertebrae and the cross-sectional area of the paraspinal muscles, including the autochthonous muscles and the psoas muscle.
• Glucose metabolism was evaluated using the oral glucose tolerance test and analysed using homeostasis model assessment 2 calculations to estimate insulin sensitivity and resistance from fasting plasma insulin, connecting peptide, and glucose levels.

TAKEAWAY:

• Women who breastfed for more than 8 months demonstrated a significantly greater decrease in PDFF of the lumbar vertebrae over 5 years than those who breastfed for 8 months or less (P = .03), even after adjusting for age and BMI at baseline (P = .03). A longer duration of breastfeeding also increased the odds of a greater reduction in PDFF of the lumbar vertebrae (odds ratio [OR], 1.12; P = .04).
• PDFF of the paraspinal muscles decreased significantly from baseline to 5 years with a longer duration of breastfeeding (P ≤ .04); PDFF of the autochthonous muscles showed a significant reduction independent of BMI and age at baseline (P = .03). Women who breastfed for more than 8 months had higher odds of decreased fat infiltration in the autochthonous muscles (OR, 1.39; P = .04).
• The cross-sectional area of the paraspinal muscles increased significantly from baseline to 5 years among women who breastfed for a longer duration (P < .01).
• The long-duration breastfeeding group showed significantly lower insulin resistance (P = .02) and higher insulin sensitivity (P = .01) at baseline than the short-duration breastfeeding group.

IN PRACTICE:

"[The study] findings may indicate a potential association of longer BF [breastfeeding] duration (> 8 months) and favourable bone and muscle composition, as well as aspects of maternal metabolic health, compared to shorter BF duration (≤ 8 months)," the authors wrote, emphasising on the importance of research with larger cohorts.

SOURCE:

This study was led by Nina Hesse, Department of Radiology, LMU University Hospital, Munich, Germany. It was published online on November 11, 2025, in the European Journal of Radiology.

LIMITATIONS:

This study had a relatively small sample size; the absence of prepregnancy data and postpartum weight trajectories and unmeasured confounders, such as dietary habits and the return of menses, limited the interpretation of PDFF changes. The lack of data on bone mineral density from DEXA or quantitative CT prevented the validation of vertebral bone marrow PDFF in postpartum women. The analysis did not differentiate between exclusive and partial breastfeeding due to the absence of detailed records.

DISCLOSURES:

No funding information was provided for this study. The authors declared having no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.