“It also includes some photos of female nipples, but photos in the context of breastfeeding, birth giving and after-birth moments, health-related situations (for example, post-mastectomy, breast cancer awareness or gender confirmation surgery) or an act of protest are allowed. Nudity in photos of paintings and sculptures is OK, too.”
Article source: https://www.huffingtonpost.co.uk/entry/florence-pugh-mocks-instagram-nipple-policy-with-valentino-show-post_uk_62ca9d52e4b04516846391e8