Evidence and unknowns for the relevancy of applying current parenteral nutrition support recommendations among infants born less than 750 g or younger than 25 weeks' gestation: A narrative review.

With advancements in neonatal care, the viability of extremely low-birth-weight (ELBW) infants, especially those born extremely preterm, is increasing. However, specific recommendations for managing parenteral nutrition (PN) support in nanopreterm infants (<750 g or <25 weeks' gestation) are lacking. We aim to evaluate current recommendations and highlight considerations for applying them to nanopreterm infants. The author team used English-language articles related to nutrition in ELBW with emphasis on nanopreterm infants, along with studies on fetal growth and metabolism. Current PN support recommendations for ELBW infants may not suit nanopreterm infants due to physiological and developmental differences. Key considerations for nanopreterm infants include: Carbohydrate: They require immediate dextrose provision with low glucose infusion rates because of limited glycogen stores, immature gluconeogenesis, and impaired glucose intolerance. Lipids: Although essential for energy storage and cell membrane integrity, the ability to metabolize them may be limited, requiring careful consideration of lipid injectable emulsion provision and dosing. Protein: Protein is crucial for growth and development. However, achieving euglycemia is essential for proper amino acid utilization, requiring a delicate balance of dextrose and protein provision. Energy: Because of lower muscle and tissue mass and immature metabolic capabilities, existing recommendations may overestimate their energy needs. Micronutrients: Exact micronutrient requirements are unknown during this specific period of fetal development. This review highlights the limitations of available PN support recommendations for nanopreterm infants. Further research is needed to establish precise guidelines that optimally meet their nutrition needs.