Are conditional defines possible?

for example:

Code:
IF PORTB.0 THEN
    DEFINE HSER_TXSTA 24h
    DEFINE HSER_SPBRG 8 
    SPBRGH=2
ELSE   
    DEFINE HSER_TXSTA 20h
    DEFINE HSER_SPBRG 64
    SPBRGH=0
ENDIF
I only ask because I wasn't sure if defines were processed in the same way as PBP commands or if they were treated specially by the compiler.