Congenital heart disease (CHD) describes the abnormalities of the heart or great vessels that are present at birth and that significantly impair the function of the cardiovascular system. It is the most common birth defect, affecting up to 2% of live-born children: according to the British Heart Foundation (BHF Statistics 2018), CHD is detected in 1 out of 180 babies (excluding bicuspid aortic valve), which translates into at least 4000 affected infants in the UK per year. CHD is diagnosed in over 8% of premature births and is a leading cause of infant mortality (up to 10% of cases). Cardiac abnormalities account for more than 9% of all stillbirths after 20 weeks and up to 4% of spontaneous miscarriages before 20 weeks of pregnancy. It is estimated that in the European Union, 3000 children with heart defects die annually as ‘terminations of pregnancy for fetal anomaly’, late fetal death or early neonatal death. Some malformations, such as aortic valve anomalies, often do not manifest at birth, and as more diagnoses are being made later in life, the number of CHD cases only increases [1–3].