I am a 23 year old female, who had an inverted nipple all my life up until I got it pierced about 3-4 years ago. It helped Keep it protruded until I got pregnant and my nipple started rejecting the piercing. Which led it to causing a literal hole in the middle of my nipple. Mind you it’s been close to 2 and half years since I’ve taken out the piercing. I also breastfed so I don’t know if that’s what caused the hole to worsen.