Significant risk factors include Prolonged mechanical ventilation High concentrations of inspired oxygen Infection (eg, chorioamnionitis or sepsis) Degree of prematurity Additional risk factors include Pulmonary interstitial emphysema High peak inspiratory pressures Large end-tidal volumes Repeated alveolar collapse Increased airway resistance Increased pulmonary artery pressures Male sex Intrauterine growth restriction Genetic susceptibility Maternal smoking The lungs of premature infants are more vulnerable to the inflammatory changes that result from mechanical ventilation.