Risk factors that affect the degree of bronchopulmonary dysplasia: Comparison by severity in the same gestational age.

Objective: To investigate the risk factors for BPD severity by gestational age (GA) and identify a way to reduce the incidence of moderate-to-severe BPD.

Study Design: This was a retrospective cohort study of very-low-birth-weight-infants (VLBWIs) delivered at 24 to 28 weeks GA from Korean Neonatal Network registry between 2013 and 2016. BPD was defined using the National Institutes of Health criteria. Study populations were divided by GA and subdivided into no/mild BPD and moderate/severe BPD. The initial statuses of all infants, including those who died before BPD diagnosis and the maternal and neonatal factors of the live infants were compared. Statistical methods included descriptive statistics, comparative tests, and logistic regression.

Results: Of 3,976 infants, 3,717 were included (24weeks, n = 456; 25 weeks, n = 650, 26 weeks, n = 742; 27 weeks, n = 836; 28 weeks, n = 1,033). The overall mortality rate was 18% and the rates by GA were 43%, 29%, 11%, and 6% in the 24-, 25-, 26-, 27-, 28-GA groups, respectively. Small for GA (SGA), treated patent ductus arteriosus (PDA), hypotension, and late-onset sepsis were significant risk factors for developing moderate/severe BPD in the 25 to 28-week GA groups in the multivariate analyses. However, for infants born at 24 weeks GA, there were no significant risk factors apart from initial resuscitation.

Conclusions: Effective initial resuscitation was the most important factor for infants delivered at 24 weeks GA determining the severity of BPD. For infants delivered between 25 and 28 weeks, judicious care of SGA infants, aggressive treatment for PDA and hypotension, and intense efforts to decrease the sepsis rate are needed to reduce the development of moderate-to-severe BPD.