Form conditional fields problem

Form conditional fields problem

Hello;
I have a select box with option Newsletter unsubscription, if selected, then show the class unsuscribereason and hide classe message else then do the reverse. The code below works fine when i click on the option Newsletter unsubscription, the problem is that this condition didn't affect the form if :

- I just visited the page where form is located;
- When i reload the page.
jQuery only apply the condition when i click an option and didn't set it as default for the form whatever situation. So i don't know how to adapt this code, maybe .change event should be replaced by something else ? 
  2. jQuery('#Subject').change(function(){
  3.     if(jQuery(this).val() == "Newsletter unsubscription")
  4.     {        
  5.         jQuery('.unsuscribereason').show();
  6.         jQuery('.message').hide();
  7.     }else
  8.     {        
  9.         jQuery('.unsuscribereason').hide();
  10.         jQuery('.message').show();
  11.     }
  12.     });