Exercise-Induced Bronchoconstriction in School-Aged Children Born Very Preterm: Prevalence and Associated Clinical Factors.

Background: Children born preterm may have persistent alterations in airway function that extend into school age; however, exercise-induced bronchoconstriction (EIB) in this population remains insufficiently characterized. This study aimed to determine the prevalence of EIB in school-aged children born at ≤32 weeks of gestation and to investigate associated clinical and neonatal factors. Methods: This single-center cross-sectional study included 42 children born at ≤32 weeks of gestation who were evaluated at 7-8 years of age. Perinatal, neonatal, respiratory, and atopic characteristics were obtained from medical records and parental reports. Baseline spirometry was performed before a standardized treadmill exercise challenge. Spirometry was repeated at 5, 10, 15, and 30 min after exercise. EIB was defined as a ≥10% decrease in forced expiratory volume in one second (FEV1) from baseline at any post-exercise time point. Results: The median gestational age was 29 (25-32) weeks, and 31% had a history of bronchopulmonary dysplasia. EIB was identified in 13 of 42 children (31%). Post-exercise EIB positivity was observed at 5, 10, 15, and 30 min in 9.5%, 16.7%, 11.9%, and 9.5% of participants, respectively. Dyspnea was the most frequent exercise-related symptom (38%). No significant differences were observed between EIB-positive and EIB-negative children regarding gestational age, birth weight, bronchopulmonary dysplasia, neonatal respiratory support, baseline pulmonary function, total IgE, or peripheral eosinophil count. Conclusions: EIB was detected in approximately one-third of school-aged children born at ≤32 weeks of gestation. These findings suggest that clinically relevant exercise-related airway hyperresponsiveness may persist into school age despite relatively preserved baseline spirometry.