In the fourth month of pregnancy, because the fetus is not growing significantly and the uterus is not particularly large, the effect on the inferior vena cava reflux is not obvious and should not cause severe edema. Mild edema is normal if it can be relieved after rest. However, if the edema is more serious and cannot be relieved after rest, pathological factors are considered. The most common cause of pathological edema is the rapid growth of the fetus in the fourth month of pregnancy, which leads to hypoproteinemia and edema caused by insufficient nutrition of pregnant women. At this time, it is necessary to enhance nutrition, eat more nutritious food, eat more milk, lean meat, egg yolk can supplement the body’s nutrition, improve the edema caused by malnutrition. It is also necessary to pay attention to a low-salt diet, as excessive salt intake can also lead to edema.