While previous research has suggested that body thinness is related to subsequent linear growth in children, it is unclear whether thinness at birth is related to linear growth in newborns and catch-up growth in small-forgestational age newborns. Drawing on data from a longitudinal growth study of 3,650 full-term Swedish babies, this study examines linear growth from birth to 6 months of age in three groups of newborns with short ( 2 SDS) body length for gestational age. Among infants short at birth, the Benn Index (kg/m2.69) at birth was not related to the odds of short stature ( 0.10). Nonetheless, the Benn Index was positively related to growth velocity in the first 6 months of life in the short (p = 0.060), appropriate (p