I remember talking to a GI (gastro-intestinal) MD about a year or two ago
that said that milk production had indeed been a "negative" side-effect of
his patients taking Reglan.  It certainly would be for non-lactating folks!

 His only response about giving it to our lactating moms was that it could
lead to depression in the long-term.  And, as stated by someone else, the
milk production decreases as the patient is weaned from it.

Janet