Purpose: Meconium aspiration syndrome (MAS) occurs when aspiration of meconium itself or meconium-stained amniotic fluid enters into the airways. The relationship between MAS and how they affect the respiratory outcome after recovery from MAS remains unknown. The purpose of this study was to determine the type of lower respiratory tract illness (LRTI) in those surviving MAS survivors and to find out whether any clinical findings or treatment determine the type of LRTI.

Methods: We used the Catholic Medical Center?s clinical data warehouse to review data from 4 university hospitals. We first included 1,331 newborns born between March 2016 and February 2021 with diagnostic codes including labor and delivery complicated by fetal stress (distress), intrauterine hypoxia, and neonatal aspiration syndromes. We finally included 239 patients who visited the outpatient clinic with diagnosis of pneumonia, acute bronchitis, acute bronchiolitis, and asthma, according to the Korean Standard Classification of Diseases.

Results: We observed a significantly higher number and fraction of eosinophils at birth in the bronchitis group. We also found significantly lower levels of white blood cells in the asthma group. After a regression analysis, we found that mechanical ventilation and steroid usage for treatment for of MAS was significantly related to bronchitis, and that antibiotics treatment acted as a protective factor for bronchiolitis.

Conclusion: Laboratory findings and treatment at birth in infants with MAS appear to have impact on determining LRTI in those who survived MAS.