To determine, in the postsurfactant era, the incidence and clinical characteristics of infants with atypical versus traditionally defined bronchopulmonary dysplasia (BPD) among premature infants with birth weights <1251 g.
Retrospective cohort study.
A single regional neonatal intensive care unit (level III/IV).
Two hundred thirty-two premature infants <1251 g at birth consecutively admitted during a 2-year period.
Incidence of classic BPD and atypical chronic lung disease (CLD) (occurring without preceding respiratory distress or after recovery from respiratory distress).
Among 177 infants <1251 g who survived to 28 days, 27 (15%) had atypical CLD and 61 (34.5%) had classic BPD. Atypical CLD infants were significantly heavier and more mature than classic BPD infants (mean birth weights, 922 ± 152 g vs 854 ± 173 g; and mean gestational age, 26.8 ± 1.3 weeks vs 26.1 ± 1.6 weeks). Median duration of ventilator support (31 days; range, 2 to 127 vs 42 days; range, 4–145 days) and oxygen therapy (30 days; range, 11 to 163 vs 48 days; range, 19–180 days) were shorter in atypical CLD infants than in classic BPD infants.
Atypical CLD comprised 31% of total cases of CLD. Atypical CLD appears to be less severe than classic BPD. These data suggest that initial, acute lung injuries are not the sole antecedents of neonatal CLD.