NPPB and Patent ductus arteriosus: In this study, the serum NT-proBNP value of premature infants in the PDA group was higher than that in the aPDA group regardless of 3d or 5d after birth; ROC curve analysis showed that the serum NT-proBNP level of 3d and 5d after birth had both a predictive value for PDA High, the sensitivity and specificity of prediction are above 92%, suggesting that serum NT-proBNP levels at 3d and 5d after birth are helpful for early prediction of PDA.