Small Nipple Ring
Rejecting nipple piercing. Once the rejection process has moved this far, switching in a properly sized ring (there's nothing wrong with the ring in this photo) won't stop the problem.
If Nipple Piercing rings are too small in diameter, the placement will be problematic and migration or rejection can follow. It is essential, especially in female nipple piercings, to avoid a small nipple ring, and that the jewelry be large enough to allow the ring to both sit comfortably and move freely. A ring that is too small will put uneven pressure on the piercing, increasing the chances of migration and rejection. In addition, the jewelry will sit low and be quite difficult to move.
One reader describes their experience with migration after such a piercing,
"I have rather large breasts and nipples. When I had my nipples pierced horizontally the piercer used large rings, but not large enough to account for nipple enlargement as my nipples enlarged about 20-30% after piercing. Nearly two years later I didn't even know they had migrated due to pressure from the rings being too small. I was having a lot of issues (soreness, bleeding) so I went to another piercer who showed me they had migrated and stopped. He suggested barbells would stop these problems. So I had them changed. After the barbells were in I could see how much they had migrated — they were both crooked and I was upset I might have to take them out. I have since had them pierced vertically with barbells. Thanks to my wonderful piercer and his great piercing ability you almost cannot tell the horizontal piercings are crooked. My advice to everyone: If you have the gut feeling that you don't like the person to whom is going to pierce you, walk out and find someone who makes you feel comfortable, who is honest, and who has a great piercing ability."
If the jewelry is placed at a proper depth, the jewelry will move easily, like an old-fashioned door knocker. However, if so much of the ring is buried that there is no longer an effective "hinge", any movement of the jewelry will cause irritation and internal stresses (as you can see in the last picture).
A piercer in Toronto wanted to point out that this is can also occur in men, writing,
"This is also an issue with male nipple piercings. Just yesterday one of my clients — a young man — came to me for a follow-up appointment. He'd been pierced with a 3/8" 14 ga barbell. He decided to switch to a 3/8" CBR on his own. Due to the curve of the jewelry, that diameter did not fit properly and the piercing started to migrate. It is important to avoid terms like 'especially female' as, in my experience, the public will ignore the 'especially' part. Present it like it is — a problem regardless of gender."
Finally, improper jewelry really doesn't look very good. No experienced reputable piercer should be making this mistake. If you visit a studio and see pictures like this in the studio, avoid it.