PAPPA and coronary artery disorder: Among the double-index diagnostic models, the AUC values for diagnosing fetal CHD using serum POSTN combined with serum PAPPA, amniotic fluid POSTN combined with PAPPA, ECG combined with POSTN or PAPPA were 0.85, 0.821, and 0.913, respectively, with sensitivities, specificities, negative predictive values(NPV), and positive predictive values(PPV) ranging between 70 and 90%.