Bronchopulmonary dysplasia in extremely premature infants: A scoping review for identifying risk factors

Background: With recent advances in respiratory support and improved survival rate of periviable infants, the etiology of bronchopulmonary dysplasia (BPD) might be changing over time. The aim of this scoping review was to screen available evidence regarding perinatal and neonatal risk factors associated with the development and severity of BPD for future revision of BPD classification. Methods: The eligibility criteria of the studies were year of publication between 2016 and 2021; setting of a developed country; English or Japanese as study language; and randomized controlled, cohort, or case-control design. The titles and abstracts of the studies were screened by independent reviewers. Results: Of 8,189 eligible studies, three were included for severe BPD and 26 were included for moderate BPD. The risk factors of severe BPD were male sex, iatrogenic preterm birth, maternal hypertensive disorders of pregnancy (HDP), low gestational age, small-for-gestational-age (SGA) birth weight, mechanical ventilation on day 1, and need for patent ductus arteriosus (PDA) management. The risk factors of moderate or severe BPD included male sex, premature rupture of membranes, chorioamnionitis, maternal HDP, SGA birth weight, bubbly/cystic appearance on X-ray, and PDA management. Conclusion: We identified several risk factors for BPD that might predict respiratory outcomes earlier. We plan to confirm whether those factors could actually be predictors of BPD using the large cohort.