co-sleeping

[<lfontes@xxxxxxx>]

I am looking for the latest research or official (e.g. from 
a body of physicians) recommendation regarding co-sleeping 
of parents and children.

At what ages is it found to be helpful/harmful and under 
what circumstances? (e.g. helpful if mother is nursing, 
harmful if mother is obese, not recommended beyond X years 
old, etc.).

At this point I can use an "official word" more than 
anecdotal info. this is for a book and I could use this help 
quick.
thanks y'all!

Lisa fontes, Ph.D.