Severity of Bronchopulmonary Dysplasia Among Very Preterm Infants in the United States.

Background And Objectives: The National Institute of Child Health and Human Development Neonatal Research Network recently proposed new, severity-based diagnostic criteria for bronchopulmonary dysplasia (BPD). This study provides the first benchmark epidemiological data applying this definition.

Methods: Retrospective cohort study of infants born from 22 to 29 weeks' gestation in 2018 at 715 US hospitals in the Vermont Oxford Network. Rates of BPD, major neonatal morbidities, and common respiratory therapies, stratified by BPD severity, were determined.

Results: Among 24 896 infants, 2574 (10.3%) died before 36 weeks' postmenstrual age (PMA), 12 198 (49.0%) did not develop BPD, 9192 (36.9%) developed grade 1 or 2 BPD, and 932 (3.7%) developed grade 3 BPD. Rates of mortality before 36 weeks' PMA and grade 3 BPD decreased from 52.7% and 9.9%, respectively, among infants born at 22 weeks' gestation to 17.3% and 0.8% among infants born at 29 weeks' gestation. Grade 1 or 2 BPD peaked in incidence (51.8%) among infants born at 25 weeks' gestation. The frequency of severe intraventricular hemorrhage or cystic periventricular leukomalacia increased from 4.8% among survivors without BPD to 23.4% among survivors with grade 3 BPD. Similar ranges were observed for late onset sepsis (4.8%-31.4%), surgically treated necrotizing enterocolitis (1.4%-17.1%), severe retinopathy of prematurity (1.2%-23.0%), and home oxygen therapy (2.0%-67.5%).

Conclusions: More than one-half of very preterm infants born in the United States died before 36 weeks' PMA or developed BPD. Greater BPD severity was associated with more frequent development of major neonatal morbidities, in-hospital mortality, and use of supplemental respiratory support at discharge.