That has not been my experience.  I was told not to have anything except for clear liquids during my delivery (large canadian hospital, not long ago).  I asked and asked, since my low sugar was becoming a problem, but no deal.  

A related pet-peeve: when going in for day surgery, you are asked have nothing to eat or drink after midnight the day before.  Which sounds reasonable, until you realize that the recommendation is the same whether your surgery is at 7am or 4pm.