
Keywords: اکوکاردیوگرافی; BPD; Bronchopulmonary Dysplasia; PHT; Pulmonary Hypertension; GA; Gestational Age; GERD; Gastroesophageal Reflux Disease; Infants; Lung; prematurity; pulmonary hypertension; risk factors; Bronchopulmonary dysplasia; echocardiography; chronic lung disease;