I did this today and got a facetious 'well, we presume we're having a baby' reply. She went on about it a bit too, as though I had asked the stupidest question in the world. I was starting to feel a bit tempted to suggest it might be a puppy, but managed not to. Now, I don't care if this woman is having a boy or a girl; tbh, I don't really care much about the situation at all. But I was trying to make polite conversation and I thought two fairly innocuous comments to make when discussing a pregnancy were 'how is the pregnancy going?' and 'do you know what you're having?'. Most people seem happy to talk about it and if they have chosen not to find out are happy to talk about that too but if it is the wrong to ask, tell me - I can take it, and I will hold my tongue in future.