Comparison of Respiratory Outcomes between Preterm Small-For-Gestational-Age and Appropriate-For-Gestational-Age Infants

Objective This study aims to determine whether preterm infants who are small for gestational age (SGA) are more likely to have respiratory distress syndrome (RDS) compared with appropriate-for-gestational-age infants. Methods Secondary analysis of a multicenter trial evaluating magnesium for neuro-protection. Nonanomalous, singleton gestations delivered between 22(0/7) and 36(6/7) weeks were included. Large-for-gestational-age infants were excluded. We performed a nested case control study. Cases were infants with RDS; controls were infants without RDS. The sample size estimates revealed 779 subjects/group were needed to achieve a 80% power to demonstrate a 1/3 difference in RDS. We fit a multivariable logistic regression model to adjust for confounders. We assessed the association of SGA with RDS and a composite adverse respiratory and neonatal outcome. Results Overall, 947 cases and 920 controls were included. The groups differed by gestational age at delivery, antibiotic exposure, mode of delivery, infant gender, and birth weight. SGA was not associated with RDS (adjusted odds ratio [aOR]: 1.07, 95% confidence interval [CI]: 0.48-2.38) or the composite respiratory (aOR: 0.87, 95% CI: 0.37-2.04) or adverse neonatal outcome (aOR: 0.65, 95% CI: 0.27-1.54). RDS and the composite respiratory outcome were most associated with earlier gestational age at delivery, cesarean delivery, and male gender. Conclusion SGA is not associated with RDS or other adverse respiratory and neonatal composites.