Factors associated with energy intake at 28 days in preterm infants: a prospective cohort study

Early energy intake is critical for growth in preterm infants, but evidence on factors affecting energy delivery in middle-income settings is limited. This study identified factors associated with energy intake at 28 days in preterm infants. Infants with birthweight ≤ 1500 g and gestational age < 33 weeks surviving to 28 days were enrolled. Serial energy and protein intake, growth and morbidities were assessed. Multiple linear and mixed-effects regression evaluated energy intake at 28 days and longitudinally, respectively. Among 168 infants, mean birthweight was 1113.5 (SD 241.9) g and gestational age 29.3 (SD 2.1) weeks. Bronchopulmonary dysplasia (BPD) occurred in 31.9% and necrotising enterocolitis (NEC) in 4.8%. Full enteral feeding and energy intake of 100 kcal/kg/day were achieved at 16.8 (SD 9.3) and 17.2 (SD 7.4) days, respectively. Energy and protein intake from parenteral and enteral nutrition remained below recommended targets during the first 14 days, while the protein-energy ratio remained inadequate through day 28. Mean growth velocity to 28 days was 5.1 (SD 3.6) g/kg/day, with a median weight z-score change of - 1.48 (IQR - 1.78 to - 1.27). After adjustment, energy intake at 28 days was lower in infants with BPD (mean difference - 11.7 kcal/kg/day, 95% CI - 23.1 to - 0.4) and NEC (- 33.3 kcal/kg/day, 95% CI - 57.3 to - 9.3).

Preterm infants experienced suboptimal early energy and protein intake and growth. BPD and NEC were independently associated with lower energy intake at 28 days, highlighting ongoing nutritional challenges, particularly in preterm infants with major morbidities.

• Optimal early postnatal growth remains challenging to attain in sick preterm infants. • Recommended energy and protein targets may remain unmet despite structured nutrition protocols.

• Lower energy intake at 28 days was independently associated with NEC and subsequent development of BPD. • Suboptimal parenteral and enteral nutrient delivery, particularly during the first 14 days, occurred alongside subsequent growth faltering.