Breasts become smaller after giving birth to a child is usually a normal phenomenon, usually due to the decline in hormone levels. Because during pregnancy the gestational sac will secrete HCG, and can maintain the ovarian corpus luteum function, resulting in the continuous secretion of progesterone, estrogen, when the mammary ducts cell stimulation will be the case of breast enlargement, so after giving birth to the body’s progesterone will decline rapidly, the glandular organization of the mammary glands so as to return to the normal size of the glands will gradually atrophy, resulting in the breasts to become smaller, so it is a normal phenomenon. In addition, if the patient breastfeeds after giving birth, the breasts will also become smaller. It is recommended that the patient maintains a good state of mind and can perform aerobic exercises such as yoga after giving birth, which can help the body recover. It is recommended to wear comfortable and appropriate size underwear after childbirth to avoid pressure on the breasts, and if there are any symptoms of physical discomfort, they should go to the hospital in time and consult the physician for guidance.