Swelling of the legs can be a sign of a variety of diseases, such as pericarditis, varicose veins, excessive secretion of estrogen in women and other causes. 1. Pericarditis: it is an inflammatory disease of the pericardium, which can be caused by infection, tumor and other factors that cause inflammatory reaction of cardiomyocytes. The main symptoms can be manifested as chest pain, cough, palpitation can be accompanied by swelling of lower limbs, dyspnea and so on. 2. Varicose veins: it is a kind of disease in which the veins are tortuous and dilated, leading to localized lesions, which can be caused by blood stagnation and weak walls of veins, etc. The main symptoms can be manifested as inflammation of lower limbs. The main symptom can be manifested as the appearance of greenish purple vein bulges on the skin of lower limbs, which are visible to the naked eye, and some of them are combined with edema of lower limbs. 3. Physiological phenomenon in late pregnancy: the uterus increases in size in late pregnancy and compresses the inferior vena cava, resulting in obstruction of blood return to the inferior vena cava; at the same time, estrogen secretion increases and aldosterone secretion increases in the period of pregnancy, which may lead to swelling of both lower limbs. These are only some of the common causes. If the swelling persists and cannot be relieved, you should go to the hospital in time and undergo the relevant examinations to clarify the cause of the disease and actively cooperate with the doctor’s treatment.