Objective: To determine whether the duration of noninvasive respiratory support exposure is associated with bronchopulmonary dysplasia (BPD) or death in preterm infants. Methods: Multicenter, retrospective study of infants born at <29 weeks’ gestation. The association between days on noninvasive respiratory support and BPD or death was determined using instrumental variable techniques and generalized propensity score matching to account for potential confounding by illness severity. Results: Among 6268 infants 36% developed BPD or died. The median duration of noninvasive respiratory support was 18 days. There was inconsistency in the association between noninvasive support and BPD or death when analyzed by instrumental variable techniques (Average Marginal Effect −0.37; 95% CI −1.23 to 0.50) and generalized propensity score matching (Average Marginal Effect 0.46; 95% CI 0.33 to 0.60). Conclusion: Findings on the association between duration of exposure to noninvasive respiratory support and the development of BPD or death were inconclusive. ClinicalTrials.gov ID: Generic Database:NCT00063063.