The earliest cord wrapping occurs around 16 weeks of pregnancy, i.e. around 4 months of pregnancy. The umbilical cord is composed of two arteries and one vein, covered with grayish white mucous membrane and surrounded by rich gelatin to protect the blood vessels. The cord wrapping around the neck will make the umbilical cord relatively short, which will affect the entry of the fetal first dewlap into the pelvis and may prolong or stop the labor process. When the umbilical cord is stretched due to the number of weeks of entanglement or too tight, or when the umbilical cord is compressed due to contractions, the fetal blood circulation is blocked and the fetus is deprived of oxygen. When intrauterine hypoxia occurs in the fetus, frequent variant decelerations can occur. Therefore, we should be highly alert to cord entrapment. When the prenatal diagnosis of cord entrapment is made, we should focus on it, especially when frequent variable decelerations appear in fetal heart monitoring, which cannot be relieved by oxygenation and changing position, the pregnancy should be terminated in time.