Bear with me on this, I am aware of how silly this sounds...
Just back from dd's 12 month check up. HV mentioned that we need to work on her speech. She's babbling but obviously not as much as she should be 
Anyway, perhaps I've been over thinking this but could this have anything to do with the fact that I am from Liverpool and her dad is from Scotland?
We even pronounce her name differently because of our accents - are we confusing her?
For example I say world, he says wurrold... :)
Wondered what your thoughts were on this...