Clinical outcomes and longitudinal growth trajectories in preterm infants fed donor human milk versus formula

This study evaluated the clinical efficacy and growth impacts of an institutional 3-week donor human milk (DHM) strategy in very low birth weight infants before and after its discontinuation due to staffing shortages and financial deficits. This retrospective study analyzed 125 consecutive very low birth weight infants from 2 eras: DHM group (n = 68; January 2020–February 2023) and Formula group (fed preterm formula; n = 57; March 2023–December 2025). The primary outcomes were necrotizing enterocolitis (NEC ≥ stage 2), cumulative 24-hour nil per os episodes, and anthropometric z -scores at birth, 3 weeks, and discharge. NEC was analyzed using Firth penalized-likelihood regression, and serial z -scores using linear mixed-effects models with formal equivalence testing at discharge. NEC occurred in 3 of 68 infants (4.4%) in the DHM group and 8 of 57 (14.0%) in the Formula group (absolute risk difference 9.6%, 95% confidence interval: −2.0 to 19.9). The preterm formula era was associated with a higher adjusted risk of NEC ≥ stage 2 (adjusted odds ratio [OR] = 6.27, 95% confidence interval: 1.37–42.71, P = .016) and with more 24-hour nil per os episodes (0.3 ± 0.5 vs 0.1 ± 0.3, P = .010). At 3 weeks, the DHM group had significantly lower z -scores for weight (–1.89 ± 0.88 vs –1.32 ± 0.97, P = .001), length (–1.49 ± 1.03 vs –1.12 ± 0.87, P = .032), and head circumference (–1.58 ± 0.79 vs –1.00 ± 0.86, P < .001). The era × time interaction was significant for all 3 measures (all P < .001), and between-era differences were no longer detectable at discharge, where z -scores were equivalent within a prespecified margin of ± 0.5 z . In this single-center cohort, the 3-week DHM protocol was associated with a lower incidence of NEC and fewer episodes of feeding intolerance, although the small number of events limits the precision of this estimate. Early growth deficits were no longer detectable at discharge under an alternating fortification protocol. Given that the bank closure stemmed from systemic infrastructure failures, sustaining donor milk programs may require national-level support.