Susan, you asked:
How do I reply to hospital nurses who think babies should be breastfed
(scheduled) according to their birthweights?  In other words, babies who
are small or large are fed every 3 hours; babies who are average are to
be fed every 4 hours etc.  Anyone know where they come up with this idea
that there is a correlation between feeding and birthweight?

There is a question which can be applied to any intervention (and imposition of schedules for feeds is an intervention) -  *What evidence is there that this intervention improves outcomes?*  This is the basis for the systematic review of research data from randomised controlled trials, and is available for anyone to read via the Cochrane Library (BMJ Publishing Group, London)
On the question of feeding schedules for neonates, the reviewer (Renfrew 1996) states:
"There are no grounds for restricting breastfeeding times in the early post-partum days.  Mothers should be encouraged to breastfeed their babies as often as they and their babies wish....  There is a dearth of information about whether or not feeding schedules are needed for small sick or pre-term babies.  In the light of the fact that feeding schedules are often imposed on these groups research is urgently required to investigate this issue."

I believe there are many practical, physical and psychological  reasons why feeding schedules have a negative impact on breastfeeding.   If health care professionals continue to ignore the evidence in situations like this they could be considered to be doing harm to the mother and baby, or at least negligent in their care.

With best wishes,
Joy Johnston, Midwife IBCLC
Melbourne, Australia