Timing of Parenteral Nutrition in Neonates, Infants, and Children: Current Evidence, Circadian Considerations, and Emerging Directions.

Despite advances in parenteral nutrition (PN) formulations, the temporal aspects of PN delivery are less defined. This review synthesizes evidence on the optimal timing of PN initiation, duration, and delivery within the 24-h day in pediatric populations. Evidence suggests that the optimal timing of PN initiation varies by age and clinical context. While early PN remains standard practice for very preterm and very low birth weight infants, delaying PN has been associated with improved outcomes in critically ill children. Continuous PN is routinely initiated in neonates and critically ill children to minimize fluid and metabolic fluctuations, whereas cyclic PN is generally used in older infants and children who are clinically stable to allow infusion-free periods and greater mobility. Despite the widespread use of overnight PN infusions in both the hospital and home settings, the clinical implications of aligning PN delivery with endogenous circadian rhythms remain very limited. Future studies should establish optimal temporal strategies for different pediatric populations and determine whether optimizing the timing, infusion pattern, and circadian alignment of PN delivery improves growth, development, metabolic health, and quality of life.