Rachel,
NPO means nothing by mouth.  Before surgery all pts. must have nothing by
mouth after midnight, that means nothing not even clear liquids.  When I used
to work in outpatient surgery in pre-op we would have many moms be very angry
due to cancellation of surgery because they fed the baby.  They would say
they didnt think Breastmilk counted, or water counted, or juice counted,
etc... anesthesia will cancel surgery if anything is given by mouth after
midnight.  The danger is aspiration of stomach contents  into the lungs.
 while aspiration of breastmilk I am sure would not be as severe as formula
or other liquids, I believe they will cancel her case if
 she nurses the baby after midnight.

Jessica Donahue RN IBCLC