It never changes though. When i had my first at 19/20 yrs old, and I went anywhere with my Mum, people would talk to her about the baby and not me. She would always tell them she was the nana, but secretly it made her feel great as she was 39 when Jordan was born. It really annoyed me though.
I am now 30 and have 4 kids and still people are shocked, I say to them get over it. I am married now, have a house and have clean kids who are fairly well behaved (they are when they are at school/kinder anyway LOL), and even if I wasn't married it wouldn't bother me. Too many people need to spend too much time worrying about things that have nothing to do with them.
Cheers Michelle
