Small bumps on the nipple can be caused by sebaceous glands, mastitis and blocked sebaceous ducts. 1. sebaceous glands: mammary glands will secrete oil to protect the nipple, thus small bumps next to the areola is a normal physiological phenomenon in addition to the hormonal changes during pregnancy will also lead to the appearance of sebaceous glands. 2. Mastitis: when the milk ducts are blocked or the milk is stagnant, there will be pimples around the nipple, accompanied by pain and itching. 3. Sebaceous duct blockage: When the sebaceous ducts on the surface of the nipple are blocked, the sebum in the mammary gland cannot be discharged out of the body, and small bumps will also appear on the nipple. They may subside on their own after some time. When there are small bumps on the nipple with pain, it is necessary to go to the regular hospital in time, to clarify the cause of the disease and active treatment.