Third-Trimester Glucose Homeostasis in Healthy Women Is Differentially Associated with Human Milk Oligosaccharide Composition at 2 Months Postpartum by Secretor Phenotype.

Human milk oligosaccharides (HMOs) are bioactive molecules in human milk that play a critical role in infant health. Obesity and associated metabolic aberrations can negatively impact lactation and alter milk composition. Here, the relationship between maternal glucose homeostasis and HMO composition from 136 healthy women was examined. Maternal glucose homeostasis (fasting plasma glucose and insulin, homeostatic model assessment for insulin resistance, and insulin sensitivity index) was evaluated at 30 weeks of gestation in healthy women (body mass index = 18.5-35 kg/m2). Human milk samples were collected at two months postpartum. HMO concentrations were measured via high performance liquid chromatography. Women were categorized into "secretor" and "non-secretor" groups based on 2'-Fucosyllactose concentrations (<100 nmol/mL, non-secretor). Pearson's correlation analysis and linear models were used to assess the relationships between maternal glucose homeostasis and HMO concentrations. In non-secretors, third trimester fasting plasma glucose and insulin were negatively associated with total HMO-bound sialic acid and concentrations of the sialylated HMOs 3'-sialyllactose and disialylacto-N-tetraose. In secretors, difucosyllactose and lacto-N-fucopentaose-II concentrations increased and sialyllacto-N-tetraose c and sialyllacto-N-tetraose b decreased as insulin sensitivity increased. This study is the first to demonstrate a relationship between obesity-associated maternal factors and HMO composition in both secretor and non-secretor populations.