Pregnant women feel out of breath when sleeping, first of all, consider physiological factors, such as an enlarged uterus, increased metabolism, postural changes, and secondly, consider disease factors, such as anemia, lung disease. 1, the uterus increases: after pregnancy, with the increase of pregnancy weeks, the size of the fetus increases, causing an increase in the volume of the uterus, the bottom of the uterus continues to grow upward, causing the diaphragm to lift, reducing the thoracic space, manifested as chest tightness, breathing difficulties, in the 32nd week of pregnancy 2, increased metabolism: during pregnancy, due to the changes in the mother’s body and the needs of the fetus growth and development, the body tissues and organs of pregnant women increased load, metabolism increased, lung ventilation increased, there will be shortness of breath, or even breathlessness; 3, postural changes: lying flat when sleeping, especially in the middle and late pregnancy, the uterus compresses the abdominal vessels, slowing down blood circulation, reducing the return The amount of heart blood, resulting in ischemia, hypoxia, dyspnea, breathlessness; 4, anemia: pregnant women need to supply themselves and the fetus required oxygen, if pregnant women are anemic, blood oxygen-carrying capacity decreases, have to increase the workload for the body to feed, so it will be breathless; 5, lung disease: pregnant women themselves poor lung function, the existence of bronchial asthma, pneumonia and even pulmonary heart disease, there will be breathlessness. When a pregnant woman has a difficult breathing situation, she can try to adjust her position, such as lying on the left side. If the symptoms disappear within a short time and the breathing is smooth, there is no need to worry too much. If you find that there is no improvement, it is recommended that you seek medical attention to clarify the cause and give targeted treatment measures according to the test results.