Outcomes for symmetrical and asymmetrical small for gestational age preterm infants in Canadian tertiary NICUs

Abstract

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 (CI).

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 [CI]) 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."