Pregnancy is a manifestation of chest distension. This is a normal physiological phenomenon that mostly occurs in early pregnancy and belongs to early pregnancy reaction. After pregnancy, due to the fluctuation of hormone levels in the body, the rise of human chorionic gonadotropin, estrogen and progesterone will lead to congestion and edema of breast tissue, which will cause breast swelling and pain, as well as changes such as breast enlargement, darkening of the areola, obvious veins under the skin of the breast, and prominent nipples, which is a physiological phenomenon in early pregnancy. The timing of this symptom is not certain for each person and varies from person to person. Some people experience significant breast swelling and secretion of small amounts of milk right after pregnancy; others do not experience it until just before delivery. The chest swelling that appears in early pregnancy is an early pregnancy reaction, and the symptoms will slowly ease by mid-pregnancy and generally do not require treatment. If the swelling is severe, you can give appropriate hot compresses and change the appropriate underwear to wear during pregnancy. If the chest swelling is too long and the chest pain is unbearable, it is recommended to go to the hospital to improve the relevant examination to exclude the possibility of breast disease. At the same time, it is also necessary to pay attention to rest, balanced diet and fetal preservation after pregnancy. Therefore, chest distension during pregnancy is a normal physiological phenomenon that does not require treatment and can be relieved on its own as the pregnancy week progresses.