The Underlying Causes of Respiratory Distress in Late-Preterm and Full-Term Infants Are Different From Those of Early-Preterm Infants

Background: A diagnosis of neonatal respiratory distress syndrome (RDS) is common among newborns in China. Some latepreterm and full-term (LP/FT) infants with respiratory distress (RD) symptoms but not primary surfactant deficiency are also diagnosed with RDS and given exogenous surfactant replacement therapy (SRT). Objectives: An increasing number of neonatologists have proposed that RD etiologies should be specifically classified to guide clinical treatment. Methods: The therapeutic effects of SRT on infants of different gestational ages (GAs) were compared in a large retrospective multicenter cohort study performed at 26 Neonatal Intensive Care units in China. The cause of RD at different GAs was further analyzed by comparing the different risk factors closely related to RDS severity at different GAs. Results: Analysis of 1240 infants diagnosed with RDS showed that SRT was less effective in LP/FT infants than in early-preterm (EP) infants. GA< 30 weeks and no prenatal corticosteroid use were closely related to RDS severity in EP infants, whereas perinatal infection-and perinatal hypoxia-associated risk factors and a high cesarean rate were closely related to RDS severity in LP/FT infants. Conclusions: The causes of RD might differ between LP/FT and EP infants, and the diagnosis of RDS might be overused in LP/FT infants. RD in LP/FT infants is more likely related to perinatal infection, perinatal hypoxia, elective cesarean and hereditary factors, which are important causes of neonatal pulmonary edema. New strategies for the treatment of refractory RD in LP/FT infants should concentrate more on pulmonary edema and neonatal ARDS.