Dear Attie:

There was a terrific New York Times Article on recent research on the
breastmilk's ingredients, which discussed, along with lots of other
stuff, certain growth factors and hormones.  I believe that a link
between early onset of puberty and being artificially fed was discussed
in that piece.  I can't lay my hands on the article right now, but it
ran within the last 3 or 4 years, and should be pretty easy to find in
the Times index.  It was a on the front page of the Tuesday Science
Times section.

Good luck on your research.  I hope someone, with better organized
files, comes up with the exact reference.

Sincerely,

Margaret Wills
LLLL New Jersey