Check the archives for past discussion of this issue.  But briefly, I worked
with a mom with nipple ring.  She removed it about 3 mo into the preg.  The
hole closed and she went on to nurse successfully.  I followed her for 4 mo
pp and there were no problems at all with the lactation.  I was surprised.
This may not be the case in all situations, and perhaps the skill of the
piercer will be a factor.
Barbara

Barbara Wilson-Clay, BS, IBCLC
Private Practice, Austin, Texas
Owner, Lactnews On-Line Conference Page
http://moontower.com/bwc/lactnews.html