Not everyone has a problem with strangers touching their belly, but I didn't really appreciate it. Many times I would rub their belly in return. Got lots of shocked expressions, but I just asked "What's the difference?". I was never super nasty about it, but I think I got my point across. I usually did it with humor. I had never approached pregnant women before and touched their belly, so I still don't really get why people think it's appropriate. I did love all the attention I got, though I appreciated it more when it was just verbal.