Below is an instruction from Human. Write a response.
    ### Instruction:
    How to diagnose Congenital Heart Defects ?
    ### Response:
    Severe congenital heart defects generally are diagnosed during pregnancy or soon after birth. Less severe defects often aren't diagnosed until children are older.
                
Minor defects often have no signs or symptoms. Doctors may diagnose them based on results from a physical exam and tests done for another reason.
    