Optimizing the growth of very-low-birth-weight infants requires targeting both nutritional and nonnutritional modifiable factors specific to stage of hospitalization.

Background Data on how baseline characteristics, acuity, morbidity, and nutrition work in combination to affect the growth of very-low-birth-weight (VLBW, <1500 g) infants are limited. Objective We aimed to determine factors associated with in-hospital weight, length, and head circumference (HC) trajectories of VLBW infants. Methods VLBW infants (n = 316) from the GTA-DoMINO trial were included. Linear mixed-effects models assessed relations of baseline characteristics, acuity (at birth, across hospitalization), major morbidities, and nutrition (enteral feeding type, macronutrient/energy intakes) with changes in anthropometrics over hospitalization (days 1–8, 9–29, 30–75). Results Specific factors and the strength of their associations with growth depended on in-hospital time interval. Small-for-gestational-age infants experienced weight gain (4.3   g · kg⁻¹ · d⁻¹; 95% CI: 2.0, 6.5   g · kg⁻¹ · d⁻¹) during days 1–8, versus weight loss (−4.6     g · kg⁻¹ · d⁻¹; 95% CI: −5.6, −3.7     g · kg⁻¹ · d⁻¹) among appropriate-for-gestational-age infants (P  < 0.001). Positive-pressure ventilation (versus oxygen/room air) was associated with slower weight (−1.8    g · kg⁻¹ · d⁻¹) and HC (−0.25 cm/wk) gain during days 9–29 (P  < 0.001). Morbidities were negatively associated with growth after days 1–8, with patent ductus arteriosus (PDA) showing negative associations with weight (−2.7     g · kg⁻¹ · d⁻¹), length (−0.11 cm/wk), and HC (−0.21 cm/wk) gain during days 9–29 (P  < 0.001). Macronutrient/energy intakes were associated with weight across hospitalization (P  ≤ 0.01), with greater weight gain (1.3–3.0 g  ·  kg⁻¹  ·  d⁻¹) among infants achieving macronutrient/energy recommendations during days 9–29 and 30–75. Macronutrient/energy intakes were associated with HC during the first month (P  = 0.013–0.003), with greater HC gain (0.07–0.12 cm/wk) among infants achieving protein, lipid, and energy recommendations during days 9–29. Conclusions Baseline characteristics, acuity, morbidity, and nutrition factors were independently associated with VLBW infant growth. A focus on achieving macronutrient/energy recommendations and improving nutrient delivery to PDA-diagnosed infants may yield improvements to their growth. This trial was registered at www.isrctn.com as ISRCTN35317141. [ABSTRACT FROM AUTHOR]