From BIA to BMI: A New Look at Postpartum Recovery and Breastfeeding Outcomes

Background/Objectives: Successful and sustained breastfeeding depends on maternal, psychological, metabolic and obstetric factors including hydration status, body composition, gestational age at delivery and mode of delivery, which are rarely assessed together in routine postpartum care. Bioelectrical impedance analysis (BIA) provides a non-invasive assessment of hydration and tissue composition, yet its potential to support lactation outcomes remains insufficiently studied. This study aimed to evaluate the relationship between postpartum body composition, hydration status assessed with BIA, and breastfeeding duration. Methods: A total of 122 women in the early postpartum period after term singleton deliveries were enrolled, of whom 50 completed the full protocol, including a 7-month follow-up. BIA and anthropometric measurements were performed on postpartum days 2 and 3. Breastfeeding duration was assessed at 7 months via telephone interview and categorized as <6 months or ≥6 months. Two indices (PLBI and sPLBI) were calculated to describe BMI change from pre-pregnancy to 7 months postpartum. Results: Breastfeeding for ≥6 months was significantly associated with marital status, mode of delivery, lower BMI on postpartum day 2, and a positive change in the overhydration index (ΔOH). Women in this group exhibited significantly lower PLBI and sPLBI values, indicating more effective postpartum weight recovery and a greater return toward pre-pregnancy BMI. Hydration parameters derived from BIA differentiated between shorter and longer breastfeeding duration. Conclusions: Positive postpartum hydration balance (ΔOH ≥ 0) and efficient metabolic recovery, reflected by lower PLBI and sPLBI values, may support longer breastfeeding. BIA-based assessment of hydration and body composition could help identify women at higher risk of early breastfeeding cessation. Further longitudinal research is warranted to confirm the clinical utility of BIA in postpartum care and its potential role in early lactation support.