Funny and kinda annoying, but I think I know where the saying comes from. Way back when, women didn't know when they got pregnant for sure. So I think it probably originally meant "We're expecting a baby, but we're not sure when." Or at least, that's my guess. But yeah, still, just say you're pregnant or having a baby LOL!
Sleeping bag with pants...Because hopping around in a sleeping bag would look ridiculous...