Difficulty in breathing at 37 weeks of pregnancy may be caused by physiological reasons on the one hand, and on the other hand, it is possible that the pregnant woman suffers from heart and lung diseases. 1. Physiological reasons, due to the 37 weeks of the uterus increases in size, pressure on the diaphragm, thus affecting the function of the lungs and heart, and then cause breathing difficulties, some people may need to sit and breathe in order to make themselves more comfortable. 2. Heart disease, if the heart function itself is not good, such as pregnancy combined with hypertrophic cardiomyopathy, perinatal cardiomyopathy, etc., there may be accelerated heart rate or dyspnea, and need to consult a doctor. 3. Lung disease, if there is mild pulmonary edema, dyspnea may also occur. At 37 weeks of pregnancy, dyspnea is more obvious and requires prompt medical attention.