Supplementary Material for: Mode of Delivery and Incidence of Bronchopulmonary Dysplasia: Results from the Population-Based EPICE Cohort

Introduction: Bronchopulmonary dysplasia (BPD) represents a tremendous disease burden following preterm birth. The strong association between compromised gas exchange after birth and BPD demands particular focus on the perinatal period. The mode of delivery can impact on lung fluid clearance and microbial colonization, but its impact on BPD and potential trade-off effects between death and BPD are not established. Methods: A total of 7,435 live births (24+0 to 31+6 weeks postmenstrual age) in 19 regions of 11 European countries were included. Principal outcomes were death and BPD at 36 weeks. We estimated unadjusted and adjusted associations with mode of delivery using multilevel logistic regression to account for clustering within units and regions. Sensitivity analyses examined effects, taking into consideration regional variations in C-section rates. Results: Compared to vaginal delivery, delivery by C-section was not associated with the incidence of BPD (OR 0.92, 95% CI: 0.68–1.25) or the composite outcome of death or BPD (OR 0.94, 95% CI: 0.74–1.19) after adjustment for perinatal and neonatal risk factors in the total cohort and in pregnancies for whom a vaginal delivery could be considered. Sensitivity analyses among singletons, infants in cephalic presentation, and infants of ≥26+0 weeks of gestation did not alter the results for BPD, severe BPD, and death or BPD, even in regions with a high C-section rate. Conclusions: In our population-based cohort study, the mode of delivery was not associated with the incidence of BPD. The intention to reduce BPD does not justify a C-section in pregnancies where a vaginal delivery can be considered.