- Evidence suggests that a curvilinear relationship may exist between birth weight and later psychopathology. Increases in the prevalence of macrosomia and of two of its risk factors (maternal pre-pregnancy obesity and diabetes mellitus) and their amenability to intervention argue for a critical review of the association between macrosomia and mental illness. Of the nine studies in adults and six studies in youth that have examined associations between macrosomia and psychiatric disorders, seven have provided evidence suggestive of a link. Significant methodological variability and an inability to adjust for important confounders limit the findings of these studies. As a result, it remains unclear if individuals born macrosomic are at increased risk for psychopathology later in life. Future work should attempt to examine a broader range of psychiatric outcomes, use validated measures, include data on putative confounders and utilize genetically sensitive designs to assess associations between macrosomia, its precursors and later psychological and emotional functioning.