Effects of Early Enteral to Parenteral Protein Ratios on Brain Volume and Somatic Growth in Very Low Birth Weight Infants

Objective: To evaluate whether a higher proportion of enteral vs parenteral protein ratio (E:P ratio) in the first 28 days after birth is associated with increased brain volume and somatic growth in very low birth weight (VLBW; birth weight <1500 g) infants.

Study design: This was a retrospective analysis of a subcohort of VLBW infants (n = 256, gestational age mean 28.07 [SD 2.17] weeks, birth weight 1038.80 [SD 262.95] grams) from the Cincinnati Infant Neurodevelopment Early Prediction Study, a regional prospective study of infants born at ≤32 weeks' gestation. Brain magnetic resonance imaging was obtained at term-equivalent age. Macronutrient intake and growth metrics for the first 28 days were collected retrospectively. The primary outcome was total brain tissue volume. The relationships between E:P ratio, total and regional brain tissue volumes, and somatic growth were analyzed by multivariable linear regression models; composite variables were used to adjust for potential confounders including pregnancy risk factors and initial severity of illness.

Results: Higher E:P ratio was associated with increased total brain tissue volume but was not associated with change in head circumference z score. In secondary analyses, higher E:P ratio was associated with increased weight velocity. There were no significant associations between E:P ratio and change in weight or length z scores or regional brain volumes.

Conclusions: Higher E:P ratio in the first 28 days was positively associated with total brain volume and weight gain. Promoting the provision of enteral over parenteral protein may improve brain and somatic growth in VLBW infants.