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.