Look up the work of Paula Meier.  I heard her speak at a recent
conference and it was an eye-opener.  A couple of references include:
Meier, P. (1988). Bottle and breast feeding: Effects on transcutaneous
oxygen pressure and temperature in preterm infants. Nursing Research, 37,
pp36-41; and Meier, P and Anderson G. (1987). Responses of small preterm
infants to bottle and breast feeding.  MCN: American Journal of
Maternal-Child Nursing, 12, pp97-105.  Hope this helps.  Alicia.
[log in to unmask]  By the way, we are very straight-forward in our
family.  My child simply said "I want to nurse".