Early treatment with inhaled nitric oxide is not associated with improved survival among extremely preterm neonates with pulmonary hypoplasia, according to a recent study. This cohort study used data from the Pediatrix Medical Group’s Clinical Data Warehouse, a data set containing information from >350 neonatal intensive care units in 35 US states and Puerto Rico. Since inhaled nitric oxide was not randomly prescribed, researchers used 1-to-1 propensity score matching to reduce the imbalance of measured covariates between the 2 treatment groups. The initial, unmatched cohort included singleton neonates who were born between 22 and 29 weeks’ gestation, had a birth weight of ≥400 g, were diagnosed with pulmonary hypoplasia as a cause of their respiratory distress, remained free of major anomalies, and were discharged between January 1, 2000, and December 31, 2014. They found:

• Among 92,635 neonates,767 (0.8%) were identified with pulmonary hypoplasia who met all study inclusion criteria, of whom 185 (0.2%) were exposed to inhaled nitric oxide.
• Among 151 matched pairs of exposed and unexposed neonates, there was not a significant association between inhaled nitric oxide use and mortality.