Early parenteral nutrition is associated with improved growth in very low birth weight infants: a retrospective study

Objective: To assess the association between early initiation of parenteral nutrition (PN) and body growth in preterm infants with very low birth weight (VLBW).

Design: Causal inference analysis with confounders preselected by causal diagram based on the NeoNutriNet cohort containing data of infants born between 2011 and 2014 from 13 hospitals from 5 continents.

Patients: Neonates with birth weight ≤1500 g.

Interventions: PN initiated within the first day of life (early PN) versus within day 2-5 (delayed PN).

Main outcome measures: The primary outcome was body weight z-scores at postmenstrual age (PMA) 36 weeks or early discharge or death, whichever comes first (WT z-score END). Secondary outcomes included WT z-scores at week 1 and 4 of life (WT z-scores CA1 and CA4), corresponding growth velocities (GVs), mortality and incidence of necrotising enterocolitis (NEC), and duration and episodes of antibiotic treatment.

Results: In total, 2151 infants were included in this study and 2008 infants were in the primary outcome analysis. Significant associations of early PN were found with WT z-score END (adjusted mean difference, 0.14 (95% CI 0.05 to 0.23)), CA4 (β, 0.09 (0.04 to 0.14)) and CA1 (0.04 (0.01 to 0.08)), and GV PMA 36 weeks (1.02 (0.46 to 1.58)) and CA4 (1.03 (0.56 to 1.49), all p<0.001), but not with GV CA1 (p>0.05). No significant associations with mortality, incidence of NEC or antibiotic use was found (all p>0.05).

Conclusions: For VLBW infants, PN initiated within the first day of life is associated with improved in-hospital growth.