An atypical pattern of chronic lung disease (CLD) has been described in preterm infants and a potential association with intrauterine inflammation has been proposed. We aimed to describe patterns of CLD, to determine the incidence of atypical CLD, and to compare the distribution of various perinatal factors in infants with classic and atypical CLD. Information about demographics, respiratory status and various perinatal variables was collected for all neonatal admissions <1250 g. CLD was defined as oxygen dependency at 28 days of age. Ninety (51%) survivors at 28 days of age developed CLD; of these 37 (41%) were classified as atypical CLD. Factors significantly and independently associated with development of atypical CLD included being inborn, receiving natural surfactant, fewer days of mechanical ventilation within the first 28 days of life and higher birthweight. Chorioamnionitis, postnatal infection and symptomatic PDA were not found to be significantly associated with atypical CLD. Atypical CLD is a common pattern of prolonged oxygen dependency in preterm survivors and is a feature of larger, more mature babies. Our findings do not support the hypothesis that exposure to intrauterine inflammation is an important aetiological factor in the development of atypical CLD.