Background: Emerging evidence indicates that metabolic hormones are present in human milk, but, to our knowledge, no studies have investigated the impact of maternal metabolic status assessed during pregnancy on insulin and adiponectin concentrations in milk.
Objectives: We aimed to investigate the associations of prenatal metabolic abnormalities with insulin and adiponectin in human milk and to compare the concentrations of these hormones in early and mature milk.
Design: Pregnant women aged ≥20 y with intention to breastfeed and without preexisting type 1 or 2 diabetes were recruited. Participants (n = 170) underwent a 3-h oral-glucose-tolerance test at 30 wk (95% CI: 25, 33 wk) gestation and donated early (the first week postpartum) and mature (3 mo postpartum) milk.
Results: Adiponectin and insulin concentrations in early milk were higher than those in mature milk (both P < 0.0001). Prenatal metabolic abnormalities, including higher pregravid BMI (β ± SEE: 0.053 ± 0.014; P = 0.0003) and gravid hyperglycemia (0.218 ± 0.087; P = 0.01), insulin resistance (0.255 ± 0.047; P < 0.0001), lower insulin sensitivity (-0.521 ± 0.108; P < 0.0001), and higher serum adiponectin (0.116 ± 0.029; P < 0.0001), were associated with higher insulin in mature milk after covariate adjustment. Prenatal metabolic measures were not associated with milk adiponectin, but obstetrical measures that included nulliparity (0.171 ± 0.058; P = 0.004), longer duration of gestation (0.546 ± 0.146; P = 0.0002), and unscheduled cesarean delivery (0.387 ± 0.162; P = 0.02) were associated with higher adiponectin in early milk after covariate adjustment, including the time elapsed from delivery to milk collection.
Conclusion: Maternal prenatal metabolic abnormalities are associated with high insulin concentrations in mature milk, whereas only obstetrical variables are associated with adiponectin concentrations in early milk.
Trial registration: ClinicalTrials.gov NCT01405547.