The reason why pregnant women feel out of breath may be physiological factors, such as the uterus increases in size and compresses the diaphragm, causing poor breathing, or pathological factors, such as the pregnant woman herself suffers from heart disease and so on. 1. Physiological factors: during pregnancy, with the increase of pregnancy, especially in the middle and late pregnancy, the uterus will increase, the uterus will increase upward pressure on the diaphragm, resulting in pregnant women breathing poorly, so pregnant women will feel out of breath. 2. Pathological factors: when a pregnant woman suffers from heart disease such as hypertension, myocarditis, cardiomyopathy, etc., due to the impaired function of the heart, resulting in the heart pumping blood can not meet the needs of the body, coupled with the increase in nutritional requirements during pregnancy, resulting in ischemia and hypoxia, so suffering from cardiac disease, you may also feel out of breath. When feeling out of breath during pregnancy, pregnant women should go to the hospital for further examination and treatment under the guidance of professional doctors.