Supplementary Material for: Maternal and Neonatal Factors Associated with Delayed Closure of Ductus Arteriosus in Term-Born Neonates: Insights from the Copenhagen Baby Heart Cohort Study

Background The prenatal shunt, ductus arteriosus (DA), typically closes during the cardio-pulmonary transition at birth. We evaluated maternal and neonatal factors associated with delayed closure of DA in term-born neonates. Method We conducted a retrospective cohort study that included full-term neonates from the prospective observational Copenhagen Baby Heart cohort study. We assessed the association between maternal and neonatal factors and delayed ductal closure. Results We included 19,566 neonates, of whom 48% were female. Echocardiography was performed at a median age of 12 (IQR:9-15) and eight (IQR:2-13) days for neonates with no DA and an open DA, respectively. Associations with delayed ductal closure included maternal obesity adjusted risk ratio=2 (95%CI:1-3.8), maternal hypothyroidism during pregnancy aRR=2.02 (95%CI:1.2-3.4), low Apgar 2.6 (95%CI:1.2-6), high weight aRR=1.81(95%CI:1.2-2.6), and length at birth aRR=1.7(95%CI:1.1-2.6). Conclusion The identified risk factors for delayed ductal closure in term-born neonates may help increase clinical attention and improve neonatal care.