• prenatal diagnosis
• congenital heart disease
• fetal echocardiography
• delivery
• pulse oximetry

Congenital heart disease (CHD) is considered major if it requires cardiac surgery or catheter intervention or results in death in the first year of life, while it is defined as critical if these occur in the first 28 days. Current strategies to increase early diagnosis of such defects involve improving antenatal screening programmes and implementing neonatal screening by pulse oximetry. Structural forms of critical CHD are usually associated with a duct-dependent lesion. Within this group, the spectrum of outcome varies, from guarded outlook such as in hypoplastic left heart syndrome (HLHS) to conditions with better outcome such as complete transposition of the great arteries (TGA).

Eckersley and colleagues1 report the results of a population-based study carried out in New Zealand (2006–2010), where one in five neonates with critical CHD had late diagnosis (after discharge from hospital following birth or at postmortem examination), while the remainder were diagnosed early (prenatally or before discharge). For these potentially critically ill infants, the authors showed an impact of timing of diagnosis (early vs late) on 1-year mortality. Such an impact was more significant in isolated critical CHD (early diagnosis; 12%, 95% CI 9% to 17% vs late diagnosis; 29%, 95% CI 20% to 41%), highlighting the role of associated syndromes and major extracardiac abnormalities on overall infant mortality. It follows that for critical CHD, isolated or not, early diagnosis is better and every effort should be made to achieve this goal. However, despite being diagnosed early, some neonates may still die if prompt cardiac intervention is not available. In the …