The goal of preterm nutrition in achieving growth and body composition approximating that of the fetus of the same postmenstrual age is difficult to achieve. Current nutrition recommendations depend largely on expert opinion, due to lack of evidence, and are primarily birth weight based, with no consideration given to gestational age and/or need for catch-up growth. Assessment of growth is based predominately on anthropometry, which gives insufficient attention to the quality of growth. The present paper provides a review of the current literature on the nutritional management and assessment of growth in preterm infants. It explores several approaches that may be required to optimise nutrient intakes in preterm infants, such as personalising nutritional support, collection of nutrient intake data in real-time, and measurement of body composition. In clinical practice, the response to inappropriate nutrient intakes is delayed as the effects of under- or overnutrition are not immediate, and there is limited nutritional feedback at the cot-side. The accurate and non-invasive measurement of infant body composition, assessed by means of air displacement plethysmography, has been shown to be useful in assessing quality of growth. The development and implementation of personalised, responsive nutritional management of preterm infants, utilising real-time nutrient intake data collection, with ongoing nutritional assessments that include measurement of body composition is required to help meet the individual needs of preterm infants.

Actual intakes of nutrients, analyzed using a nutrition phase approach to evaluating nutrition support, enabled a more infant-driven rather than age-driven application of nutrition recommendations. This approach unmasked nutrient deficits occurring during the transition phase. Overcoming nutrient deficits in this nutrition phase should be prioritized to improve the nutrition management of preterm infants.

The optimal composition of standardized parenteral nutrition (SPN) is not yet known, contributing to nutrient deficit accrual and growth failure, with the period of parenteral nutrition weaning, i.e., transition (TN) phase, being identified as particularly vulnerable. We created a comprehensive nutrition database, representative of the nutritional course of a diverse range of preterm infants (n = 59, birth weight ≤ 1500 g, gestation < 34 weeks) by collecting hourly macronutrient intake data as part of a prospective, observational study over 19 months. Using a nutrient modeling technique for the TN phase, various amino acid (AA) concentrations of SPN were tested within the database, whilst acknowledging the nutritional contribution from enteral feeds until target AA intakes were consistently achieved. From the modeling, the AA composition of SPN was determined at 3.5 g/100 mL, which was the maximum to avoid exceeding target intakes at any point in the TN phase. However, in order to consistently achieve target AA intakes, additional nutritional strategies were required, which included increasing the exclusion of enteral feeds in fluid and nutrient calculations from <20 mL/kg/day to <40 mL/kg/day, and earlier fortification of breastmilk at 80 mL/kg/day. This data-driven nutrient modeling process supported the development of an improved SPN regimen for our preterm population in the TN phase.

A structured, focussed, multimodal approach to enhance breastmilk production has shown potential for producing positive end outcomes, particularly, a significant reduction in duration of hospitalisation.