Swelling in late pregnancy may be physiological swelling, or it may be caused by pathological factors such as hypoproteinemia due to malnutrition and hypertension in pregnancy. 1. Physiological edema: due to changes in hormone levels during pregnancy, sodium and water retention in the interstitial space of the tissues can be caused, thus leading to edema. In addition, the enlarged uterus compresses the pelvic blood vessels, which can cause obstruction of vascular reflux, and can also lead to swelling of the lower limbs. 2. Hypoproteinemia: During pregnancy, the nutritional consumption is too large, if the protein intake is insufficient, it can lead to hypoproteinemia, which can also lead to edema in late pregnancy. 3. Hypertension in pregnancy: it is a group of diseases in which pregnancy and elevated blood pressure coexist, and most of them are accompanied by proteinuria, which can lead to hypoproteinemia, which manifests itself in symptoms such as elevated blood pressure, edema of the lower extremities, and decreased urine output. It can also lead to swelling in late pregnancy. There are many other causes of swelling in late pregnancy, which should be emphasized, and timely consultation should be made to identify the cause of the disease and further treatment or therapy as prescribed by the doctor.