Personally I find the concept of having sex with a preggers prossie about as appealing as hardsports which I happen to think is downright disgusting. Considering the potential dangers associated with simply being a prossie alone such as STD/STI's, violent punters, rough/harmful sex, and so on, I believe the risks posed to an unborn child make it very much irresponsible to continue 'working' while pregnant.
Also, though it is obviously of no true concern of mine as I ain't the babie's daddy, but I would hope that the prossie(s) in question would at least save a majority of the proceeds made during her pregnancy for the kid for like education, new car, etc, as IMO she is in a sense pimping her unborn baby....