Wikipedia has this to say about breastfeeding and nipple piercing:
“Nipple piercing and breastfeeding
A common question among women who consider nipple piercings is how it may affect breastfeeding. There is no evidence to suggest that proper nipple piercings can cause any complications with lactation. A letter in JAMA suggests improperly pierced nipples and scarring may result in blocked ducts.
Nipple jewelry may harm an infant during breastfeeding.
However, it is recommended that good care is taken to prevent infection by using a piercing professional and good body piercing aftercare. Frequent re-piercings can also damage the nipple and cause complications. It is also recommended that the piercing be healed before breastfeeding. Most body piercing professionals will refuse to pierce a pregnant woman for this reason and because piercing causes stress on the body that could potentially complicate a pregnancy.
Several complications have been noted involving breastfeeding with a piercing present, so it is recommended to remove nipple jewelry before nursing. Several complications resulting from nursing with nipple jewelry inserted can include poor latch, slurping, gagging, and milk leaking from the baby’s mouth.
It can also be a potential choking hazard for the baby. As the baby sucks, the ends on a barbell (if worn) may come loose and could possibly lodge in the baby’s throat (a captive bead ring, properly inserted, would lessen the risk of anything becoming loose, falling out, and lodging in the throat). The baby’s gums and tongue as well as the soft and hard palate could be injured by the jewelry.
The LLL have a more informative article with some useful links. http://www.llli.org/FAQ/pierced.html including one to this incredible article Nipple Piercing: Is It Compatible with Breastfeeding? by Jahaan Martin
that goes into the history of piercing. http://www.llli.org/llleaderweb/LV/LVJunJul99p64.html I didn’t know it was fashionable amongst Victorian Society Women!
And for a more personal view in Issue 4 of New Beginnings 2009 there is an online article called “Is there breastfeeding during or after tattooing and nipple piercing?
The full article can now be read online