Respiratory distress syndrome is associated with increased morbidity and mortality in late preterm births.

Background: Respiratory distress syndrome is strongly associated with prematurity, including late preterm births. Respiratory distress syndrome has been shown to be associated with certain neonatal morbidities and mortality, but these associations are not well described among late preterm births.

Objective: We sought to determine the association between respiratory distress syndrome and adverse neonatal outcomes among late preterm (34-36 weeks) born singleton neonates.

Study Design: This is a retrospective cohort study using California's linked vital statistics and patient discharge data (2008-2019). We included singleton, nonanomalous births with a gestational age of 34-36 weeks. Outcomes of interest were interventricular hemorrhage, necrotizing enterocolitis, retinopathy of prematurity, neonatal sepsis, length of hospital stay, neonatal death, and infant death. Chi-square and multivariable Poisson regression analyses were used to examine the association of respiratory distress syndrome with outcomes at each gestational age. Adjusted risk ratio and 95% confidence interval values were estimated.

Results: A total of 242,827 births were included, of which 11,312 (4.7%) had respiratory distress syndrome. We found that among neonates with respiratory distress syndrome, necrotizing enterocolitis was higher at 35 weeks (adjusted risk ratio, 3.97 [95% confidence interval, 1.88-8.41]) and 36 weeks (adjusted risk ratio, 4.53 [95% confidence interval, 1.45-14.13]). Intraventricular hemorrhage, retinopathy of prematurity, neonatal sepsis, and length of hospital stay were significantly higher at 34-36 weeks of gestation in neonates with respiratory distress syndrome. Neonatal death was significantly higher among neonates with respiratory distress syndrome at 35 weeks (adjusted risk ratio, 3.04 [95% confidence interval, 1.58-5.85]) and 36 weeks (adjusted risk ratio, 3.25; 95% confidence interval, 1.59-6.68). In addition, infant death was significantly higher at 35 weeks (adjusted risk ratio, 2.27 [95% confidence interval, 1.43-3.61]) and 36 weeks (adjusted risk ratio, 2.60 [95% confidence interval, 1.58-4.28]).

Conclusion: We found that respiratory distress syndrome was associated with intraventricular hemorrhage, retinopathy of prematurity, and sepsis at 34-36 weeks of gestation, whereas respiratory distress syndrome was associated with neonatal death, infant death, and necrotizing enterocolitis at 35 and 36 weeks. Clinicians should keep these outcomes in mind when making decisions about delivery timing, the potential benefits of antenatal steroids in pregnancies in the late preterm period, and the management of respiratory distress syndrome in late preterm neonates.