Fetal arrest after 20 weeks of pregnancy is called fetal death in utero; it may occur after 5 months of pregnancy, i.e. after 20 weeks of pregnancy, caused by many reasons, such as fetal factors, maternal factors, environmental factors, etc. When fetal movement disappears and the uterus no longer increases in size, fetal death in utero is suspected and should be determined by ultrasound examination. The risk of fetal death in the fifth month of pregnancy may be increased by maternal infections such as toxoplasmosis, rubella virus, cytomegalovirus, and uterine malformations. In addition, poor maternal habits during pregnancy, such as smoking and drinking alcohol, can also lead to fetal death; 3. Environmental factors: such as long-term exposure to radiation, noisy environment, can increase the risk of fetal death in utero. After pregnancy, we should pay attention to more rest, proper exercise, eat more fresh fruits and vegetables, stay away from harmful environment, avoid overwork, keep a happy mood and regular life to avoid the occurrence of fetal death in utero.