Outcomes for Symmetrical and Asymmetrical Small for Gestational Age Preterm Infants in Canadian Tertiary NICUs

Objective This study aimed to compare the outcomes for symmetrical (sSGA) versus asymmetrical (aSGA) small for gestational age (SGA) < 32 weeks preterm infants. Study Design A total of 12,179 eligible infants admitted to the Canadian tertiary neonatal intensive care units (NICUs) over a 7-year-period in the Canadian Neonatal Network database were subcategorized as aSGA (n = 536), sSGA (n = 732), or appropriate for GA (AGA, n = 10,911). Baseline demographics, mortality, and major morbidities were compared using multivariable analysis to calculate adjusted odds ratios (AOR) and 95% confidence interval (Cl). Results sSGA had higher GA (p < 0.01) and more antenatal tobacco exposure (p = 0.03). Although both the SGA groups had worse outcomes than AGA controls, aSGA versus sSGA comparison revealed lower odds (AOR [Cl]) for mortality and chronic lung disease (CLD) for aSGA in the entire cohort (0.45 [0.27, 0.75] and 0.61 [0.44, 0.84], respectively) as well as for infants < 28 weeks GA (0.50 [0.27, 0.92] and 0.47 [0.29, 0.77], respectively). aSGA infants < 28 weeks GA had comparable outcomes to AGA except higher odds for CLD (1.61 [1.13, 2.27]). sSGA infants needed longer hospital stay and had higher use of oxygen and continuous positive airway pressure than aSGA. Conclusion Among SGA infants < 32 weeks GA, significant intragroup differences exist in the neonatal outcomes and hospital resource utilization depending upon the presence or absence of relative "head sparing."