Infants born small for gestational age (SGA) are a heterogeneous group. Both the timing and duration of the intrauterine insult determine the physical condition and body composition of the infant at birth. Infants with symmetrical intrauterine growth retardation (IUGR) have a similar body composition at birth to weight-matched infants born appropriate for gestational age. However, these infants are more likely to remain shorter and lighter than normal infants. In contrast, infants with asymmetrical IUGR have reduced fat deposition but are more likely to exhibit catch-up growth during the first few months of life. The low mortality and morbidity rates in infants born SGA observed in recent studies are linked to their appropriate perinatal management, including adequate early nutritional support.