Breast Milk at Early Postpartum

Objective—The presence of appetite hormones, namely glucagon-like peptide-1 (GLP-1), peptide YY (PYY) and leptin in breast milk may be important in infant feeding regulation and infant growth. This study evaluated whether concentrations of GLP-1, PYY and leptin change across a single feeding (from fore- to hindmilk), and are associated with maternal and infant anthropometrics. Design and Methods—Thirteen postpartum women (mean ± SD: 25.6 ± 4.5 y, 72.0 ± 11.9 kg) provided fore- and hindmilk samples 4-5 weeks after delivery and underwent measurements of body weight and composition by Dual X-ray Absorptiometry. GLP-1, PYY, and leptin concentrations were measured by radioimmunoassay, and milk fat content was determined by creamatocrit. Results—Concentration of GLP-1 and content of milk fat was higher in hindmilk than foremilk (p≤0.05). PYY and leptin concentrations did not change between fore- and hindmilk. Both leptin concentration and milk fat content were correlated with indices of maternal adiposity, including body mass index (r = 0.65-0.85, p<0.02), and fat mass (r = 0.65-0.84, p<0.02). Hindmilk GLP-1 was correlated with infant weight gain from birth to six months (r = −0.67, p=0.034). Conclusion—The presence of appetite hormones in breast milk may be important in infant appetite and growth regulation