摘要Objectives We aimed to evaluate the risk factors for moderate-to-severe bronchopulmonary dysplasia(BPD)and focus on discussing its relationship with the duration of initial invasive mechanical ventilation(IMV)in very preterm neonates less than 32 weeks of gestational age(GA).Methods We performed a prospective cohort study involving infants born at 23-31 weeks of GA who were admitted to 47 different neonatal intensive care unit(NICU)hospitals in China from January 2018 to December 2021.Patient data were obtained from the Sina-northern Neonatal Network(SNN)Database.Results We identified 6538 very preterm infants,of whom 49.5％(3236/6538)received initial IMV support,and 12.6％(823/6538)were diagnosed with moderate-to-severe BPD symptoms.The median duration of initial IMV in the moderate-to-severe BPD group was 26(17-41)days,while in the no or mild BPD group,it was 6(3-10)days.The incidence rate of moderate-to-severe BPD and the median duration of initial IMV were quite different across different GAs.Multivariable logistic regression analysis showed that the onset of moderate-to-severe BPD was significantly associated with the duration of initial IMV[adjusted odds ratio(AOR):1.97;95％confidence interval(CI):1.10-2.67],late-onset neonatal sepsis(LONS),and patent ductus arteriosus(PDA).Conclusion In this multicenter cohort study,the duration of initial IMV was still relatively long in very premature infants,and the longer duration of initial IMV accounts for the increased risk of moderate-to-severe BPD.