Background: We evaluated if the number of days of exposure to a hemodynamically significant patent ductus arteriosus (hsPDA) is associated with bronchopulmonary dysplasia (BPD) and/or mortality in preterm infants.

Methods: We conducted a retrospective cohort study of preterm infants (birth weight ≤ 1500 g or gestational age < 30 weeks), admitted between January 2017 to December 2022. HsPDA was defined using Neonatologist Performed Echocardiography criteria. Logistic regression was used to assess the relationship between the duration of hsPDA and BPD/death. Additional analyses explored non-linear associations using penalized splines and quadratic functions.

Results: We included 424 neonates: 204 developed BPD/death. The duration of hsPDA was associated to increased risk of BPD/death (OR = 1.67, 95% CI 1.17-2.56, p < 0.001), adjusted for birth weight, 5' APGAR score, IVH, durations of mechanical and non-invasive ventilation. We found a progressive increase in the OR for BPD/death during the first week of exposure, followed by a plateau.

Conclusions: The duration of exposure to hsPDA is associated with adverse neonatal outcomes, (BPD/ death). The risk progressively increases during the first week of exposure followed by a plateau. These findings suggest that the first week of exposure may represent a critical window of opportunity. Conclusions: The duration of exposure to a hemodynamically significant PDA is associated with an increased risk of BPD/death. This risk progressively rises during the first week of exposure and then plateaus thereafter. This study explores the association between BPD/death and the duration of exposure to a hemodynamically significant PDA, longitudinally assessed using a comprehensive echocardiographic protocol. The findings suggest the first week of exposure to a hemodynamically significant PDA is a critical window for interventions to impact outcomes. Future research should focus on identifying high-risk population and developing targeted treatments during this pivotal period.