Well, not quite the same thing, but in one episode of The Practice (and who knows how accurate that is) a pregnant woman who was a heavy drug user was going to be charged with administering drugs to a minor.

In Winnipeg last year there was a very controversial case about a pregnant woman who had a glue-sniffing problem, and whether or not she should be forced into treatment for the sake of the unborn baby. In the end, I believe they did force her into treatment.