The Association of Human Milk Appetite-Regulating Hormones with Infant Growth and Eating Behaviors to Age Six Months

Background/Objectives: Appetite-regulating hormones are bioactive components of human milk. We tested the associations of leptin and adiponectin with infant growth and eating behaviors to age 6 months. Methods: In a cohort of 70 healthy, full-term infants and their mothers, human milk adiponectin and leptin were assayed at age 2 months (m). At infant ages 2, 4, and 6 m, infant anthropometry was obtained, mothers reported feeding frequency, duration, and breastfeeding intensity and completed the Baby Eating Behavior Questionnaire (Enjoyment of Food, Food Responsiveness, and General Appetite), and infant sucking vigor using an artificial nipple (burst duration and sucking frequency) was measured. Mothers reported demographics, gestational diabetes and pre-pregnancy body mass index (BMI), gestational age, and infant birthweight. Multivariate models evaluated predictors of leptin and adiponectin, and associations of leptin and adiponectin with infant growth and eating behaviors. Results: Human milk leptin was predicted by maternal BMI (β = 0.02) and breastfeeding intensity (β = -0.32). Regarding infant growth, infant weight-for-age and weight-for-length z-scores at 6 m were predicted by leptin (β = 0.91 and β = 1.22, respectively) and adiponectin (β = 0.01 and β = 0.01, respectively). Regarding infant eating behaviors, feeding duration at 2 m and feeding frequency at 4 m were predicted by adiponectin (β = 0.03 and β = -0.02, respectively). Conclusions: Human milk leptin and adiponectin may contribute to weight gain in early infancy, but the effect does not appear to be mediated substantially by infant eating behaviors. Further investigation into the metabolic programming of early infant weight gain is warranted.