Background: Pneumothorax is an abnormal accumulation of air in the pleural space, between the visceral and parietal pleura, occurring more frequently in the neonatal period. This study aimed to describe the characteristics of affected newborns and evaluate possible risk factors for its development.Method: We conducted an observational study with retrospective data collection of all newborns who developed pneumothorax during hospitalization in a Portuguese level II Neonatal Intensive Care Unit (NICU) from 2015 to 2025. Statistical analysis was done using SPSS 28®.Results: A total of 54 newborns were diagnosed with pneumothorax, 37 (68.5%) male and 20 (37.0%) had low birth weight (<2500g, LBW). Twenty-seven (50.0%) were preterm, with a median gestational age of 34 weeks. Delivery was dystocic in 36 (66.7%) cases, including 30 caesarean sections (55.6%).Prior to pneumothorax, 36 (66.7%) patients were receiving ventilatory support. All patients exhibited respiratory distress, predominantly grunting in 29 (53.7%) and tachypnea in 18 (33.3%). Pneumothorax was mainly unilateral in 49 (90.7%) cases, affecting the right hemithorax in 27 (55.1%). Eleven (20.4%) newborns developed tension pneumothorax, significantly associated with cardiopulmonary arrest (p = 0.04).Regarding treatment, 30 (55.6%) received conservative management, 21 (38.9%) required aspiration, and 16 (29.6%) required chest tube placement. Chest tube placement was significantly associated with prematurity (p=0.004) and LBW (p=0.014). Eight patients required transfer to a level III NICU, with no deaths reported.Median hospital stay was 11.5 days and was significantly longer in patients with tension pneumothorax (p = 0.003) or those requiring invasive treatment (p < 0.001).Conclusion: Neonatal pneumothorax predominantly affects preterm and LBW infants and is frequently associated with respiratory distress. In our sample, prematurity and LBW also increased the likelihood of requiring invasive interventions. Thus, early recognition and appropriate management are crucial to improve outcomes in this population.
