There are many reasons for fetal death in the womb, including: 1. Maternal factors: systemic diseases of the mother, such as heart and lung diseases, liver and kidney diseases, immune diseases, endocrine diseases, unhealthy habits, including smoking, alcoholism, drug abuse, malnutrition and possible sexually transmitted diseases, etc., are called high-risk groups for fetal death in the womb. 2, fetal factors: fetal malformations: trisomy 21, Turner’s syndrome (45XO); non-fetal malformations: fetal edema, fetal infections (toxoplasmosis, etc.). 3, uterine factors: uterine rupture, etc. 4, umbilical cord factors: no umbilical cord, umbilical cord rupture, umbilical cord vascular embolism, umbilical cord prolapse. Umbilical cord entanglement, umbilical cord true knot. It is when the baby ties itself in a knot and breaks its own blood source. 5.Placental abnormalities: placenta hypofunction, placenta abruptio, placenta praevia, placental infarction. 6, other factors: such as hyperemesis, HELLP syndrome, trauma. Please ask your doctor at that time and the pathology result at that time for the specific reason.