Do be happy when your child (or pet or partner or extended family member or whatever) is healthy again. Health is usually too undervalued in our world today.
Don't ask any woman if she is expecting. Ever. Doesn't matter how obvious it is. One just do not do it. It doesn't matter how happy the person is, if she actually is expecting. let her tell you. It is not fun to hear if you want to pregnant but can't. And it ain't fun IF ONE JUST IS A LITTLE TOO CHUBBY IN THOSE AREAS.
Don't ask, OK?!
Louise Dock 
Oh yes, I got asked that once – about a year after our third chid was born. It didn't worry me all that much, but the person who asked me looked about 6 months pregnant herself (and wasn't!)
Well did not either. but it is just one of those things one shall learn not to ask. 🙂
Haha! That is awkward–I've seen it happen. Also, never, assume that you are talking to a Grandmother–as in, "How old is your grandson?" Don't ask it! It's just as likely to be his mother!