Comparison of Lung Ultrasound Scores With Clinical Models for Predicting Bronchopulmonary Dysplasia：A Multi-center Prospective Cohort Study

All enrolled infants underwent LUS examination performed by two ultrasound physicians. Monitoring included a complete lung scan in the first 24 hours of life (T0) and at day 3 (T1). All neonates underwent weekly ultrasound examinations until 36 weeks postmenstrual age (T2, T3…), so that the T2 scan was carried out at the end of the first week of life. LUS was performed according to a standardized protocol \[13\] when the neonate was in a quiet state, during routine clinical care to minimise discomfort. All ultrasound images and videos were digitally recorded, anonymised, and reviewed by a senior independent ultrasonographer blinded to patients' clinical information. Each lung was divided into three regions according to the anterior and posterior axillary lines and the mammary line. The regions were the upper-anterior, lower-anterior, and latera regions.