This is the largest antenatal series of double aortic arch (DAA). It shows that in the vast majority of cases both arches are patent prenatally, but postnatally the left arch is atretic in most patients, supporting the theory of differential growth of the arches. Postnatal cases of DAA with atretic left can be misinterpreted as right aortic arch and thorough assessment by computed tomography (CT) is required. What are the clinical implications of this work?This work will help and guide antenatal counseling and postnatal management of cases of DAA. Based on our findings, the recommendation is for these patients to be delivered at hospitals where neonatal support is available, to have early postnatal pediatric cardiology review and to undergo CT irrespective of the presence of symptoms or not.