Lingustic Confusion

I feel like I've written a lot of posts this week about things that are not clothes nor fromage, my favourite topics. So in keeping with that theme, I want to talk about the phrase "in hospital". I mention it because I was reading the news just now and an article from msn.ca talked about a man being '"in hospital". A few years ago in a linguistics class our professor informed us that this is a British and, therefore Canadian expression. I have to say it befuddled me then, and it befuddles me now. I have never, ever heard a Canadian person say "in hospital". I don't know, maybe people in other parts of Canada people say this? So, if there are any Canadians out there reading this, tell me, do you or does anyone you know say "in hospital"? And, if not, is it a bit pretentious to use it for writing news articles or is this just a case of different registers?