An in-depth nutritional assessment requires dietary, anthropometric, biochemical, and clinical data. However, the taking of anthropometric and biochemical measurements is difficult; therefore, nutritional assessment in neonates receiving intensive care treatment is frequently confined to detecting fluctuations in weight gain and in caloric intake. Nonetheless, it is necessary for the clinician to be able to assess the neonate's nutritional status because of the potentially serious sequelae of malnutrition on multiple organ systems and the importance of growth (especially brain growth) to developmental outcome. The provision of energy and nutrients at levels to support growth and development is the goal of nutrition support for VLBW infants.

Nutritional assessment includes considering the length of gestation and adequacy of intrauterine growth as well as nutrient tolerance. Static assessment (current balance between intake and output) as well as a dynamic assessment (evaluation of infant's growth over time or growth velocity) of each infant are both important. Also, the nonnutritional factors such as disease state, morbidities, and medications must be considered.

Body weight

Weight gain is the most frequently used anthropometric measure. It is important to use the same scale, obtain weight measurements at the same time each day to avoid diurnal variations, and indicate any equipment being weighed (especially arm boards and dressings); if equipment is not recorded, changes in weight may be spurious. In preterm infants, weight gain should be expressed on a gram per kilogram per day basis.