Factors defining the high risk population
| Fetal factors | Maternal factors | Ultrasound findings | |
| Extracardiac anomalies | Family history/Maternal CHD | Increased nuchal fold, suspicious four chamber scan | |
| Abnormal chromosomes | Diabetes mellitus | Non-diagnostic scan | |
| Multiple fetal pregnancy | Autoimmune antibodies | “Soft” diagnostic markers—for example, echogenic cardiac foci, short femurs, echogenic bowel, symmetrical growth restriction | |
| Fetal cardiac arrhythmia | Drugs—for example, lithium, anticonvulsants | ||
CHD, congenital heart disease