DSDR KB:

As you are probably aware, NCHS no longer makes 'exact dates of occurrence' data available in the vital statistics microdata files (birth, death, etc.):

http://www.cdc.gov/nchs/about/major/dvs/NCHS_DataRelease.htm

However, that does not mean it is impossible to get exact dates of occurrence data.

Data from states include exact date of occurrence, e.g., before the data are compiled into a national file. One state that is publicly available is North Carolina via Odum Institute:

http://arc.irss.unc.edu/dvn/dv/NCVITAL/faces/SearchPage.jsp?mode=1&collectionId=530

I have confirmed that mm/dd data exist in the 1998 file.