World Health Organization classes of pregnancy risk
| Class 1: Risk is considered equivalent to that in the general population |
| Uncomplicated, small, or mild pulmonary stenosis, patent ductus arteriosus, mitral valve prolapse |
| Repaired simple lesions, eg, atrial septal defect, ventricular septal defect, patent ductus arteriosus, total anomalous pulmonary vein drainage |
| Isolated premature ventricular beats and atrial ectopic beats |
| Class 2: Small increased risk of morbidity and death |
| Unoperated atrial septal defect |
| Repaired tetralogy of Fallot |
| Most arrhythmias |
| Class 2 or 3: Moderate increased risk of morbidity and death, depending on the patient |
| Mild left ventricular impairment |
| Hypertrophic cardiomyopathy |
| Native or tissue valvular heart disease (not including class IV valvular disease) |
| Marfan syndrome without aortic dilation |
| Heart transplant |
| Class 3: Significantly increased risk of morbidity and death |
| Mechanical valves |
| Systemic right ventricle (ie, repaired congenital lesions) |
| Cyanotic heart disease |
| Post-Fontan operation |
| Complex congenital heart disease |
| Class 4: Pregnancy contraindicated |
| Pulmonary hypertension |
| Severe systemic ventricular dysfunction (left ventricular ejection fraction < 30%) |
| Severe left heart obstruction |
| Marfan syndrome with dilated aorta (> 40 mm) |
| Previous peripartum cardiomyopathy with residual impaired left ventricular function |
Adapted from information in reference 33.