World Health Organization classification of maternal cardiovascular risk
| Class I |
| Uncomplicated, small or mild pulmonary stenosis, patent ductus arteriosus, or mitral valve prolapse; successfully repaired simple lesions (atrial or ventricular septal defect, patent ductus arteriosus, anomalous pulmonary venous return) Cardiovascular risk: No increased risk of maternal mortality, possible mild increase in morbidity |
| Class II |
| Unrepaired atrial or ventricular septal defect; repaired tetralogy of Fallot; supraventricular tachycardia Cardiovascular risk: Small increased risk of maternal mortality, moderate increase in morbidity |
| Class II–III |
| Mild left ventricular dysfunction; native or tissue valvular heart disease not considered World Health Organization class I or IV; Marfan syndrome without aortic dilation; aorta less than 45 mm in association with bicuspid aortic valve; repaired coarctation of the aorta; hypertrophic cardiomyopathy Cardiovascular risk: As in class II or III, depending on individual |
| Class III |
| Mechanical valve; systemic right ventricle with good or mildly reduced function; Fontan circulation without complication; unrepaired cyanotic heart disease; other complex congenital heart disease; aortic dilation 40 to 45 mm in Marfan syndrome; aortic dilation 45 to 50 mm in bicuspid aortic valve disease; previous peripartum cardiomyopathy with complete recovery of ventricular function Cardiovascular risk: Significantly increased risk of maternal mortality or severe morbidity. Expert counseling required. If pregnancy continues, intensive specialist cardiac and obstetric monitoring needed throughout pregnancy, childbirth, and for 6 weeks afterwards |
| Class IV |
| Pulmonary arterial hypertension from any cause; severe systemic ventricular dysfunction (ejection fraction < 30%, New York Heart Association functional class III-IV); systemic right ventricle with moderate or severely reduced function; Fontan circulation with any complication; severe mitral stenosis; severe symptomatic aortic stenosis; Marfan syndrome with aortic dilation more than 45 mm; aortic dilation more than 50 mm in bicuspid aortic valve disease; native severe coarctation of the aorta; previous peripartum cardiomyopathy without complete recovery of ventricular function Cardiovascular risk: Pregnancy is contraindicated because of extremely high risk of maternal mortality or severe morbidity. If pregnancy occurs, discuss termination. If pregnancy continues, care as for class III |
Information from reference 13.