Not being able to get up for air at 39 weeks of pregnancy may be caused by the uterus enlarging and compressing the heart and lungs, or it may be caused by severe anemia, heart disease and lung disease. 1. The uterus compresses the heart and lungs: When you are pregnant, the uterus will continue to increase in size, and by the time you reach the late stages of pregnancy, the uterus has already enlarged to a certain extent. The enlarged uterus causes the chest cavity to become smaller and the pressure on the diaphragm to increase, thus affecting the cardiopulmonary activities. In addition, the increasing size of the fetus will lead to an increase in the amount of oxygen required by the body, which will lead to the symptoms of dyspnea. 2. Severe anemia: Pregnant women do not get enough iron during pregnancy, which may lead to anemia, and anemia can also cause dyspnea. 3. Heart disease and lung disease: pregnant women who suffer from congenital heart disease, chronic obstructive pulmonary disease, etc. may also cause dyspnea. The phenomenon of 39 weeks pregnant can not come up for air, should go to the hospital in time for examination, clear the cause of the disease and then under the guidance of the doctor for treatment.