Chest nipple pain may be caused by clothing discomfort, pregnancy or nipple inflammation and other factors. 1. Clothing discomfort: nipple pain may be caused by long-time friction of the nipple due to wearing too tight clothing, poor quality clothing or too loose clothing. 2. Pregnancy: After some women become pregnant, the level of estrogen and progesterone in the body will rise. The rising hormone level will promote the development of breasts, which may lead to nipple pain. 3. Nipple Inflammation: Nipple inflammation may be caused by bacterial infection of the nipple, which may be accompanied by redness, swelling and enlargement of the nipple. Chest nipple pain may also be triggered by breast hyperplasia, breast tumor or traumatic impact, and other factors, you need to go to the hospital for examination, according to the cause of treatment.