The prevalence of intra-uterine ductal dysfunction is unknown and the clinical consequences are poorly understood. The aim of this study was to investigate the echocardiographic (ECHO) abnormalities and outcomes of this rare phenomenon. Retrospective analysis of foetal (n = 602) and neonatal ECHO databases (n = 1477) between 1998 and 2007. Clinical and imaging studies were reviewed for pathology due to or associated with premature closure of the duct. Twelve cases were identified. Eight (1.3%) were diagnosed pre-natally at a median gestational age of 29.0 weeks (range: 20.0-37.5 weeks). Four neonates (0.3%) with significant cyanosis and absence of the arterial duct were also included. The most common ECHO features were: excessive right ventricular (RV) hypertrophy (100%), more than expected tricuspid and pulmonary regurgitation (100% and 92%, respectively), and right atrial dilation (75%). Premature induction of delivery was advised for five patients. Neonatal therapy consisted of observation and oxygen administration (n = 7), ventilation with pulmonary vasodilators (n = 5), and one required extracorporeal membrane oxygenation. There were three deaths due to respiratory failure with severe pulmonary hypertension. During follow-up, two children required additional right heart procedures and one developed a non-compaction cardiomyopathy. Foetal premature closure of the arterial duct causes stress at different foetal ages and many different levels of the right heart and pulmonary circulation, resulting in a wide range of secondary pathology. Disproportionate RV hypertrophy is the most common finding. Clinical outcomes range from mild symptomatology to lethal respiratory insufficiency.