Nipple enlargement after pregnancy may be a normal physiological change of the breast after pregnancy, or it may be a symptom of mastitis, breast hyperplasia and other diseases. 1. Nipple changes after pregnancy are mainly due to changes in progesterone in the body after pregnancy. The increased secretion of progesterone tends to stimulate the breasts, which then leads to nipple enlargement, which is a normal physiological phenomenon that mainly prepares for breast milk secretion after delivery. 2. After pregnancy, the body’s estrogen and progesterone levels increase dramatically causing an imbalance of estrogen and progesterone, which makes it easy for breast enlargement to occur, and breast enlargement is cyclical and has localized swelling and pain. 3. Mastitis not only leads to nipple enlargement, but also localized redness, swelling, heat, pain and other reactions. In addition, pregnant nipples should also consider other causes such as tumors, symptoms must go to the hospital, under the guidance of the doctor’s medication, not their own indiscriminate use of drugs.