Sex differences in infant blood metabolite profile in association with weight and adiposity measures

BACKGROUND Nuclear magnetic resonance (NMR) metabolic profiling quantifies a large number of metabolites. From adolescence, specific metabolites are influenced by age, sex and body mass index; data on early-life metabolic profiles are limited. We investigated associations between sex, birth weight, weight and adiposity with NMR metabolic profile at age 12 months. METHODS The plasma NMR metabolic profile was quantified in infants (n = 485) from the Barwon Infant Study. Associations between 74 metabolites and sex, birth weightz-score and 12-month measures (weightz-score, skinfold thickness, weight-for-lengthz-score) were examined using linear regression models. RESULTS Several cholesterol and fatty acid measures were higher (0.2-0.3 SD) in girls than in boys; we observed modest sex-specific associations of birth weightz-scores and 12-month sum of skinfold thicknesses with metabolites. The pattern of associations between weightz-score and weight-for-lengthz-score with metabolites at 12 months was more pronounced in girls, particularly for fatty acid ratios. CONCLUSIONS We identified sex differences in the infant metabolic profile. Sex-specific patterns observed differ from those reported in older children and adults. We also identified modest cross-sectional associations between anthropometric and adiposity measures and metabolites, some of which were sex specific.