It bugs you so much because she is over-board with it, I'm taking. Is she a first time mother?? Does the baby have Downs?? or does he just look like he could?
I have the opposite. I have people telling me I need to get my kid into modeling....and yeah - I probably could but the costs and all that goes with it...I'd rather have my kid grow up normal being a boy and not swell his head so young.
Hmmm...you could joke with her and tell her she's a little obsessed with the subject? or in time...she'll get the hint that REALLY .....he ISN'T what they are looking for. No one wants to hurt her so that's a nice way to say it. Sorry that you are the one who is bombarded with it.
I wouldn't even know what to do except nod my head and try to escape when she starts on it. Try hanging out less....or overwhelm her with links to baby modeling.. (ha - just kidding). She'll be so busy trying to make each submission deadline -she'll be too busy to hang out!
She will figure it out for herself without anyone actually hurting her feelings.
Try changing the subject or making your visits with each other farther in between. Holidays are here - good time for a break!
Sorry I don't really have a great answer for you - hope someone else does.