373 - Comparison of Growth and Metabolic Outcomes in Extremely Preterm Infants Fed Different Human Milk Fortifiers: A Retrospective Cohort Study

Publication Number: 3360.373

Alena A. Alexander, McGovern Medical School at the University of Texas Health Science Center at Houston, Sunnyvale, TX, United States; Sepideh Saroukhani, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States; Mar Romero-Lopez, UT Health. Houston, Houston, TX, United States; Lindsay F. Holzapfel, McGovern Medical School at the University of Texas Health Science Center at Houston, Houston, TX, United States

Background: Human milk fortifiers enhance the nutritional content of human milk. Our center transitioned from Fortifier A (bovine-derived) providing 3.58g protein/100kcal to Fortifier B (bovine-derived) which offers 3.4g protein/100kcal in its standard and 4g protein/100kcal in its high protein formulation. Fortifier B, when considering both standard and high protein, has a higher average protein content than Fortifier A. Higher protein in new generation fortifiers may increase the risk for metabolic acidosis, a relationship that has not been well investigated.

Objective: This study compares metabolic and growth outcomes in extremely preterm infants fed two bovine-derived human milk fortifiers.

Design/Methods: This retrospective cohort study included infants < 28 weeks gestational age (GA) born from 5/1/2023-4/17/2024, fed Fortifier A, and from 4/18/2024-5/31/3025, fed Fortifier B. Clinical and laboratory data were collected daily for the first 14 days after birth and weekly thereafter until 36 weeks postmenstrual age (PMA). Infants who received both fortifiers, were not fortified prior to 36 weeks PMA, or died before fortification were excluded. The primary outcome was the incidence of metabolic acidosis (pH < 7.25, bicarbonate < 22, base deficit > 5) requiring intervention after initiation of fortification (sodium bicarbonate supplementation, transition to a different fortifier, or unfortified human milk). Secondary outcomes included growth (weight, length, head circumference), incidence of feeding intolerance, and late onset sepsis evaluation by 36 weeks PMA. Linear and logistic regression analyses were performed for continuous and categorical outcomes, respectively.

Results: Among 108 eligible infants, the Fortifier A group (n=51, mean ± SD GA 25.5 ± 1.7 weeks, birthweight 800 ± 217g) had similar baseline characteristics compared to Fortifier B group (n=57, GA 25.4 ± 1.6 weeks, birthweight 818 ± 251g) (Table 1). The incidence of metabolic acidosis requiring intervention was higher in the Fortifier B group (n=13, 22.8%) compared to Fortifier A (n=3, 5.9%) with odds ratio 4.7 (95% CI 1.3 - 17.7, p=0.01). The incidence of feeding intolerance, late onset sepsis evaluation, and growth at 36 weeks PMA were comparable between groups.

Conclusion(s): Preliminary findings suggest infants receiving Fortifier B had a fourfold higher risk of metabolic acidosis requiring intervention compared to Fortifier A, despite similar growth outcomes through 36 weeks PMA. Further analysis will assess whether this risk differs between the Fortifier B standard and high protein formulations to account for differences in nutrient composition.

Table 1. Early perinatal and neonatal characteristics


Table 2. Clinical outcomes at 36 weeks postmenstrual age