Postnatal growth is a crucial in premature infants as it could be correlated with the long-term cognitive development. Recent data from the literature show that it is possible - with appropriate nutritional care - to reduce the initial weight loss and to ensure that the growth deficit accumulated is then less important than was previously observed. The quantitative objective is to achieve growth that is at least equivalent to that of the fetus (12-18 g/kg.day according to postconceptional age). Children often grow slowly during the first 10 days of life, so they accumulate a growth deficit that should be compensated secondarily. Therefore, optimum postnatal growth is 20 g/kg.day, rather than 15 g/kg.day. It is also important to assess the quality of growth, particularly fat free mass. The objective of nutritional care is dual: a sufficient weight gain (close to fetal growth rate) but also a relevant body composition. However, there is very little data on body composition of premature babies at discharge. It is now possible to measure quickly (one minute), simply and noninvasively using pediatric air-displacement plethysmography. Previous studies using more complex search techniques to implement (dual energy X-ray absorptiometry) showed excessive body fat at discharge in premature babies. Reference values collected using pediatric air-displacement plethysmography were published in 2011. Nutritional practices and strategies have significantly evolved in the past years to support such objectives: improvement of early parenteral nutrient intake, new fortifiers for human milk, new preterm formulas and early beginning of enteral nutrition. Individualized fortification of human milk helps to provide preterm infants with sufficient amount of nutrients. The modern nutritionnal care in preterm infants results in earlier and higher protein and energy intakes than previously performed. It improves some anthropometric parameters but little is know about body composition at discharge. Furthermore, exposition to high nutrients intake could lead to metabolic and hormonal imprinting with an increased risk of diabetes and cardio-vascular diseases in adulthood.