Swelling from the 20th week of pregnancy may be normal, such as increased circulating blood volume, uterine enlargement and other reasons, or it may not be normal, such as caused by kidney disease. 1. Increase in circulating blood volume: the fetus grows and develops gradually during the 20th week of pregnancy, the uterus, breasts and other organs need extra blood to maintain the metabolism of the mother and promote the growth and development of the fetus, the amount of circulating blood in the body will increase gradually, and the intertissue fluids will also increase, and the body will show swelling. 2. Uterine enlargement: the uterus will increase significantly during the 20th week of pregnancy, which will compress the inferior vena cava and impede the return of blood to the lower extremities, resulting in swelling. 3. Kidney disease: 20 weeks pregnant with kidney disease, such as glomerulonephritis, due to the body of the glomerular filtration barrier is impaired, resulting in water and sodium retention, there will be swollen body manifestations. Whether or not swelling is normal at 20 weeks of pregnancy should be decided according to the cause of the disease, and any abnormality should be treated promptly.