Date Calculation

In my table I record my clients' date of birth and when they die I record their date of death. In order to calculate their age I subtract "DOD - DOB." However, it does not calculate correctly. For example, I use my DOB of "9/29/1958" and the current date(4/30/2003)and I get an age of 45.
It should be 44.
Does anyone have any ideas?
Thanks!