While pierced nipples don't typically cause any problems, a piercing on your areola, the dark area around the nipple, or the surrounding breast tissue, could be an issue. (verywellfamily.com)
Many moms with pierced nipples report leaking from the site of the piercing, but that won't impact your ability to breastfeed.» (romper.com)
If you choose to keep your jewelry out permanently until your baby is weaned, be aware that even a fully healed piercing may close and some women have noticed nipple pain in a previously pierced nipple while nursing (Wilson - Clay & Hoover, 2005). (breastfeedingtoday-llli.org)