Pregnant women sweat on their chests when they sleep, which may be related to factors such as higher body temperature of pregnant women, and because the sweat glands in the chest position are highly secreted, so the performance is more obvious after sweating. Common causes of sweating are as follows: 1, body heat: the basal metabolic rate increases during pregnancy, changes in the function of the phytonotropic system, blood vessels are in a dilated state, increased blood flow to the skin, hyperadrenocorticism, accelerated metabolic rate, higher than normal body temperature; 2, uterine compression: as the uterus continues to grow during pregnancy, when the fetus is too large, compression of the pelvic and abdominal vessels, blood is not able to return in a timely manner In addition, the sweating is caused by the lack of blood and oxygen, which causes ischemia and hypoxia, neurological changes and increased secretion of sweat glands; 3, physical weakness: early pregnancy reaction is more serious in some pregnant women in early pregnancy, insufficient nutritional intake and weakness of Qi and blood causing sweating; 4, calcium deficiency: instead of skeletal changes in the short term, there will be abnormal neural regulation and excitation of the parasympathetic nerves that govern the sweat glands causing sweating. In addition, it may be related to the relatively high temperature of the living environment, wear more, cover thicker, etc. The temperature and humidity of the living environment should be appropriate, clothing should be loose and breathable to avoid binding, and the cover should be thin and thick when sleeping.