Anna,
Good question.  I guess there is a slight correlation, however, preemies, as
do term babies, lose up to 10% of their birth weights during the first week
of life.  Babies in utero, do not.  For example, my first daughter WAS two
weeks early, was born at 8lbs, 3oz, and at one week was down to 7lb, 10oz.
At her due date, she was back up at 8lb, 6oz.  As she has been big ever
since, I'm convinced she would have been well over 9lbs on her due date!

Now your question said 'preemies'.  Two weeks early isn't preemie.  My
second daughter was born 6 weeks early, at 5lb, 4oz.  She lost too, and was
down to 4lb 12oz before she 'turned'.  On her due date however, she was
9lbs.  This one is 'average', so I'm not so sure she'd have been as big on
her due date, despite the loss.  To me, it looks like the growths inside
versus outside differ, at least in my experience.  Plus, preemies gains will
vary depending on the circumstances.  I've met some with complications who
were only about 4-5lbs on their 'due' dates.  These are the very early ones.

Does this help your curiousity?  I'm basically saying "maybe...maybe not!".
Anyway, for the record, my first was breastfed and supplemented slightly,
due to jaundice and 'ignorance' on my part.  The second was primarily
breastfed, though was given some formula against my wishes in the NICU.  She
didn't begin to gain, until I brought her home and began feeding her more
frequently, solely breastmilk, from the breast too!

Linda Coleman, NMI, West Grove, PA