PDF Margins issue

We are trying to retrieve Page margins for a pdf but every time we get the same margin details which is 72,72,90.90. I have created a file in Word with margins as 0.5 inch and also 1 inch, but on converting to pdf when we execute the below code we always get the same values.

As per the below code we are retrieving top, bottom, left and right margins but the value is always 72,72,90.90.

pdfDocument.getPages().get_Item(1).getPageInfo().getMargin().getTop();  

pdfDocument.getPages().get_Item(1).getPageInfo().getMargin().getBottom();

pdfDocument.getPages().get_Item(1).getPageInfo().getMargin().getRight();  

pdfDocument.getPages().get_Item(1).getPageInfo().getMargin().getLeft();  

Can you please guide us how to retrieve the margins set in a pdf file.

Regards,