Nutrient intake during the parenteral-to-enteral transition and longitudinal growth faltering in very preterm infants

The transition from parenteral to enteral nutrition can expose preterm infants to nutrient deficits. We characterized nutrient intake during this transition phase and investigated nutritional and clinical factors linked to longitudinal growth faltering (GF). This single-center, retrospective-prospective observational study included 190 surviving infants born before 32 weeks of gestation who achieved full enteral feeding and completed at least 30 days of follow-up. Growth faltering (GF) was defined as a decrease in weight Z-score exceeding 1.2 standard deviations from birth to discharge or 40 weeks postmenstrual age, whichever came first. We analyzed combined parenteral and enteral nutrient intakes across various enteral-volume intervals. Multivariable logistic regression was used to calculate adjusted odds ratios (aORs) with 95% confidence intervals (CIs), estimated via bias-corrected and accelerated bootstrapping. GF occurred in 84 infants (44.2%), with the most significant interval-specific Z-score decline observed between enteral volumes of 30 and 160 mL/kg/day. In unadjusted comparisons, infants experiencing GF had longer transition periods and greater average daily and cumulative energy and protein deficits during the first 30 days. However, none of the 39 volume-specific nutritional comparisons remained significant after Bonferroni correction. Faster enteral advancement was associated with a lower likelihood of GF (aOR 0.69 per 1 mL/kg/day; 95% CI 0.57-0.78). Higher protein intake at 80 to less than 120 mL/kg/day showed an exploratory association with lower odds of GF (aOR 0.39 per 1 g/kg/day; 95% CI 0.15-0.81). Male sex was associated with higher odds of GF, though with imprecise estimation (aOR 9.82; 95% CI 3.56-72.89). The association with late-onset sepsis was less stable (aOR 3.26; 95% CI 0.97-21.46). These findings advocate for close monitoring of combined nutrient intake during the transition period, though they do not establish causality. The observed association with protein intake requires independent confirmation.