Hi, Annie Furie in New Mexico!  Ginna Wall in Seattle, at University of
Washington Medical Center.  I have had some experience using Reglan with
mothers of preterm infants.  Not much success--let me re-phrase that:
even if Reglan increases the mother's milk supply, so that now she's
getting 10cc instead of 5cc per pumping, that's still not enough to supply
all the breastmilk the baby needs, is it?  So she feels disappointed.  We
don't use it much for this reason.

I've had better success when mom has a well-established supply that
suddenly drops because baby has been hospitalized or something.  Reglan,
plus a suckling infant, in these cases seems to really make a positive
difference.

Two other thoughts:  is the mother still pumping after each breastfeeding
session?  Most mothers need to be told (gently-they don't want to hear it)
that their premie is not able to remove all the milk from the breasts in
the early stages of beginning to breastfeed.  It's tempting to skip
pumping when the baby finally goes to breast, but unfortunately this
results in a drop in her milk supply!

And finally, we've learned that "every 3 hours" means vastly different
things to different people!  Make sure she is pumping 7-8 times a day.
She might see a great improvement if she gets up early in the morning to
pump.

Good luck, hope this helps!