Keywords: aortic isthmus; arterial duct; bicuspid aortic valve; coarctation of the aorta; congenital heart disease; fetus; Z-score EN aortic isthmus arterial duct bicuspid aortic valve coarctation of the aorta congenital heart disease fetus Z-score 850 856 7 12/03/20 20201201 NES 201201 CONTRIBUTION B What are the novel findings of this work? The performance of test variables was determined using receiver-operating-characteristics (ROC) curves analysis and logistic regression analysis to assess the contribution of cardiac parameters ( I Z i -scores of aortic valve diameter, pulmonary valve diameter, AD diameter, DTAA diameter, DTAA/AD diameter ratio and aortic valve/pulmonary valve diameter ratio) to the prediction of postnatal CoA. With respect to the computed I Z i -scores, the aortic valve diameter I Z i -score, DTAA diameter I Z i -score and second-trimester I Z i -score of the ratio of DTAA/AD diameters were also significantly lower in true-positive than in false-positive CoA cases (Table 1, Figure S1). Other studies8,14-16 recommend integration of the isthmus/AD diameter ratio to reduce the false-positive rate in the diagnosis of CoA, and our data using the I Z i -score of DTAA/AD diameter ratio support this, but demonstrate an overlap of measurements such that any cut-off would require compromise between diagnostic rate and diagnostic accuracy. [Extracted from the article]