I wasn't remotely worried about this until I read the 'second review' questions in the Red Book today and one of the questions is "Does your baby babble (ba-ba, da-da etc)".
DD is 6 months next week and is still at the 'aruuuu' and 'abu' stage and doesn't really say much else, although she does squeal lots when excited.
Should I be concerned? Or am I doing my usual worrying about nothing?