Breasts usually start to become engorged and swollen at the beginning of pregnancy, but the symptoms of pregnancy vary from person to person, and there are some pregnant women who do not show breast swelling. During pregnancy, the placenta secretes a large amount of estrogen to stimulate the development of the milk ducts, and also secretes a large amount of progesterone to stimulate the development of the breast follicles. The development of mammary ducts and mammary follicles will lead to breast swelling, while pituitary prolactin, human placental prolactin, insulin and cortisol will also be involved, and breast swelling is a common manifestation of early pregnancy. After pregnancy, the nipples will be enlarged and darkened, the areola color will deepen, and the surrounding sebaceous glands will increase in size, forming scattered nodular bumps. During pregnancy, the mammary glands are fully developed and ready to secrete milk breast. Women should pay attention to the protection of breasts after pregnancy, do not squeeze; in addition, try not to rub when bathing to avoid discomfort. If you have any other questions, it is recommended to consult a professional doctor for guidance.