Growth and Clinical Outcomes of Very Low-Birth-Weight Infants Receiving Acidified vs Nonacidified Liquid Human Milk Fortifiers.

BACKGROUND: Liquid human milk fortifiers are used commonly in neonatal intensive care. Use of an acidified HMF (A-HMF) is associated with transient metabolic acidosis, but whether growth outcomes differ between infants fed A-HMF vs nonacidified HMF (NA-HMF) remains unknown. METHODS: Retrospective cohort study of 255 infants born at <33 weeks' gestation and ≤1500 g who were receiving ≥75% fortified human milk on day of life 14, in a level III neonatal intensive care unit (NICU) from May 2015 to December 2018. Infants born before October 2017 (n = 165) received A-HMF, whereas infants born after October 2017 (n = 90) received NA-HMF. We used logistic regression to estimate odds of metabolic acidosis (serum bicarbonate <16 mEq/L in the first 21 days of life) in infants receiving A-HMF vs NA-HMF and linear mixed models to compare the mean size at discharge (weight, length, head z-scores) by HMF type. We adjusted models for confounders and accounted for the nonindependence of multiple births. RESULTS: Median gestational age was 28.7 weeks (range, 22.6-32.9) and birth weight 1.1 kg (range, 0.4-1.5). Infants receiving A-HMF had higher adjusted odds of metabolic acidosis than infants receiving NA-HMF (adjusted odds ratio, 2.7; 95% CI, 1.2-6.2). There were no differences between groups in size z-scores at discharge. CONCLUSIONS: In human-milkfed, very-low-birthweight infants, fortification with liquid A-HMF may contribute to metabolic acidosis in the first month of life, but this practice does not appear to impair growth through NICU discharge, compared with fortification with NA-HMF.

Associations of Growth and Body Composition with Brain Size in Preterm Infants.

OBJECTIVE: To assess the association of very preterm infants' brain size at term-equivalent age with physical growth from birth to term and body composition at term. STUDY DESIGN: We studied 62 infants born at <33 weeks of gestation. At birth and term, we measured weight and length and calculated body mass index. At term, infants underwent air displacement plethysmography to determine body composition (fat and fat-free mass) and magnetic resonance imaging to quantify brain size (bifrontal diameter, biparietal diameter, transverse cerebellar distance). We estimated associations of physical growth (Z-score change from birth to term) and body composition with brain size, adjusting for potential confounders using generalized estimating equations. RESULTS: The median gestational age was 29 weeks (range, 24.0-32.9 weeks). Positive gains in weight and body mass index Z-score were associated with increased brain size. Each additional 100 g of fat-free mass at term was associated with larger bifrontal diameter (0.6 mm; 95% CI, 0.2-1.0 mm), biparietal diameter (0.7 mm; 95% CI, 0.3-1.1 mm), and transverse cerebellar distance (0.3 mm; 95% CI, 0.003-0.5 mm). Associations between fat mass and brain metrics were not statistically significant. CONCLUSIONS: Weight and body mass index gain from birth to term, and lean mass-but not fat-at term, were associated with larger brain size. Factors that promote lean mass accrual among preterm infants may also promote brain growth.