Is there any health risk to having pierced nipples?

YES ! Nipple piercings have led to cellulitis ; abscesses. The jewelry can snag against clothing with potential of traumatic tears to the nipple. Additionally, scar tissue on the nipple or jewelry can block a milk duck ; in some cases make it more difficult to latch during breastfeeding.
Not Usually. The major health risk occurs at the time of the piercing. Infection is really the major concern. Outside of that there is no real health risk.
Yes. Cellulitis, abscess, tears if piercing gets caught on clothing , can get scarring which can affect breast feeding......
Pierced Nipple Risk. Pierced nipples liked pierced ears or any other minor surgery have the potential of infection which can lead to not being able to breast feed, noticeable scarring and any problems. These risks are increased if not done in a sterile manner.