During-Pregnancy Intervention Recommendations for Intervention During Pregnancy in Women With VHD Referenced studies that support the recommendations are summarized in Online Data Supplement 43. COR LOE Recommendations In pregnant women with severe AS (mean pressure gradient 40 mmHg, Stage D), valve intervention during pregnancy is reasonable if there is hemodynamic deterioration or if there are NYHA class III or IV HF symptoms.1 7 In pregnant women with severe rheumatic MS (mitral valve area 1.5 cm2 , Stage D) and with valve morphology favorable for PMBC who remain symptomatic with NYHA class III or IV HF symptoms despite medical therapy, PMBC is reasonable during pregnancy if it is performed at a Comprehensive Valve Center.8 12 In pregnant women with severe valve regurgitation and with NYHA class IV HF symptoms (Stage D) refractory to medical therapy, valve surgery is reasonable during pregnancy.13 16 3: Harm C-LD In pregnant women with VHD, valve surgeries should not be performed in the absence of severe HF symptoms refractory to medical Synopsis In pregnant women with severe VHD who develop se- vere, intractable symptoms despite maximal medical therapy, surgical or percutaneous intervention may be- come necessary. Recommendation-Specific Supportive Text 1. Patients with severe AS may develop progressive HF or sudden hemodynamic deterioration during the stress of pregnancy. Both open heart surgery and percutaneous balloon dilation of the aortic valve are high-risk procedures during pregnancy for both the mother and the fetus and should be performed only if there is hemodynamic deterio- ration or if there are severe NYHA class III or IV HF symptoms. The type of intervention will be dependent on the valve morphology and on the expertise of the center. 