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.The plasma NMR metabolic profile was quantified in infants (n = 485) from the Barwon Infant Study. Associations between 74 metabolites and sex, birth weight z-score and 12-month measures (weight z-score, skinfold thickness, weight-for-length z-score) were examined using linear regression models.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 weight z-scores and 12-month sum of skinfold thicknesses with metabolites. The pattern of associations between weight z-score and weight-for-length z-score with metabolites at 12 months was more pronounced in girls, particularly for fatty acid ratios.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.