After 20 weeks of pregnancy, the fetus dies in utero, which is about one in every two hundred pregnancy cases. (The death of the fetus during delivery is called stillbirth, which is also a type of stillbirth.) Since about half of the cases of stillbirth have no signs of problems during pregnancy, most parents lose their fetuses without realizing it. When fetal movement suddenly stops, pregnant women may suspect that something is wrong. More than half of stillbirths are caused by fetal hypoxia. The causes of hypoxia include placental factors such as placenta previa, early placental detachment, umbilical cord prolapse, umbilical cord knotting, and umbilical cord around the neck affecting blood supply; fetal factors such as multiple births, intrauterine growth retardation, and teratoma; maternal factors such as pregnancy-induced hypertension syndrome, diabetes, and overdue pregnancy; local uterine factors such as excessive uterine tension or strong contraction, uterine rupture, etc. After the fetus dies, the pregnant woman feels that the fetal movement has stopped, the breast swelling disappears, the uterus no longer continues to grow, the weight decreases, and the fetal heart disappears, then the possibility of stillbirth can be considered. B-type ultrasound examination indicates that the fetal movement and fetal heart disappear, and sometimes the fetal head has been deformed, which can be confirmed. Most dead fetuses can be expelled on their own. If they are not expelled within 3 weeks after death, the degenerated placenta and amniotic fluid will release thromboplastin into the maternal blood circulation, causing disseminated intravascular coagulation (DIC).