There are several possible causes of sore nipples in pregnancy: First, the development of breasts will accelerate during the period after pregnancy. At this time there will be a certain amount of milk accumulating in the breast cells to prepare nutritionally in advance for the birth of the fetus. Due to the increase in the size of the breast cells, it will compress the nerves around the breast to make people feel pain. This is a normal physiological phenomenon, not a sign of disease. Second, it may be an inflammation of the breast. Because women’s bodies are in a state of sensitization during pregnancy, their resistance is relatively weak. This, coupled with the relative instability of the body’s endocrine system, can lead to external germs infecting the breast. If the breast is infected by bacteria, it will lead to redness, swelling, swelling and pain in the breast and also pain in the nipple, which will need to be treated with certain medicines. Third, it may also be due to breast enlargement. Nowadays, the number of women with breast enlargement is increasing, and pregnant women are also prone to breast enlargement, which can also lead to nipple pain.