Most pregnant women will experience breast swelling and pain around 42 days after pregnancy, and will experience breast enlargement, obvious engorgement, darkening of the areola, and hypertrophy of the sebaceous glands on the areola to form small scattered nodular bulges, which are normal. After pregnancy, women will be affected by the increase of pituitary prolactin, placental prolactin, estrogen, progesterone, growth hormone and insulin, especially after 6 weeks of pregnancy, the level of progesterone and estrogen in the body increases, estrogen promotes the proliferation of breast ducts, while progesterone promotes the development of breast alveoli, so pregnant women will feel their breasts swollen, in fact, to prepare for breastfeeding after delivery. It is recommended that when women experience breast pain during pregnancy, they should choose supportive and soft underwear to prevent pressure and stimulation of the breasts, and they can also apply hot compresses to their breasts to relieve swelling and pain. If the breast pain is not relieved for a long time after pregnancy, or even worsens, you should go to the obstetrics and gynecology department of the hospital in time.