Purpose <p>To create an overview of the criteria used to classify small for gestational age (SGA) newborns according to their body-proportionality as either asymmetric SGA or symmetric SGA, and to create an overview of the clinical outcomes related to body-proportionality.</p> Methods <p>A scoping review was conducted using PubMed, Embase and the Cochrane Library databases. Studies were included if they described SGA newborns regardless of gestational age and if their classification on body-proportionality was given for both aSGA and sSGA. Data were screened and extracted by two independent reviewers.</p> Results <p>Of the 38,265 studies identified after deduplication, 45 were included. Body-proportionality was classified by the ponderal index (PI) in 55.6% of studies (<i>n</i> = 25), head circumference (HC) in 24.4% (<i>n</i> = 11), birth length in 11.1% (<i>n</i> = 5), birth length and HC in 4.4% (<i>n</i> = 2), birth length and PI in 2.2% (<i>n</i> = 1), and PI, brain-to-body ratio and HC/length ratio in 2.2% (<i>n</i> = 1). The most commonly reported outcomes were asphyxia, hyperbilirubinemia, hypoglycemia, mortality and respiratory distress syndrome. The results regarding the outcomes were inconsistent and contradictory.</p> Conclusion <p>Large heterogeneity in the published classifications and clinical outcomes regarding body-proportionality in the SGA newborns exists. Consensus on terms, methods and cut-off values used for body-proportionality is needed to improve future comparison of study results.</p>