Small-for-Gestational-Age Status and Adverse Clinical Outcomes in Preterm and Very Preterm Infants: A Propensity Score-Matched Cohort Study

Background/Objectives: Preterm (<37 weeks) and very preterm (<32 weeks) infants face considerably higher mortality and morbidity rates than full-term infants. We compared clinical outcomes between small-for-gestational-age (SGA) and appropriate-for-gestational-age (AGA) preterm infants. Methods: This retrospective cohort study used a prospectively collected database, obtained from 2014 to 2025. Propensity score matching (PSM), multivariate regression, and subgroup analyses of very preterm infants were performed to minimize confounding. Results: Among the 5890 neonatal admissions, 2331 preterm infants met the inclusion criteria. After PSM, 298 SGA and 298 AGA preterm infants were analyzed. Multivariate analysis showed that SGA preterm infants had significantly higher risks of the composite outcome of mortality or major morbidity (adjusted risk ratio [aRR], 1.89; 95% confidence interval [CI], 1.18–3.02), mortality (aRR, 3.53; 95% CI, 1.57–7.95), and mortality or moderate-to-severe bronchopulmonary dysplasia (aRR, 2.13; 95% CI, 1.30–3.48). In the subgroup analysis after PSM, 190 very preterm infants showed similar results, with SGA infants having increased risks of the composite outcome of mortality or major morbidity (aRR, 1.81; 95% CI, 1.02–3.23), mortality (aRR, 3.23; 95% CI, 1.09–9.62), mortality or moderate-to-severe bronchopulmonary dysplasia (aRR, 2.03; 95% CI, 1.10–3.72), and mortality or treated retinopathy of prematurity (aRR, 2.62; 95% CI, 1.03–6.65). Conclusions: SGA status is associated with a higher risk of mortality and major morbidity in preterm and very preterm infants. In resource-limited settings, the focused management of SGA infants is critical to improving short- and long-term outcomes.