Fetal immobility may be caused by physiological factors or certain pathological factors, such as fetal distress, umbilical cord around the neck, etc. If you find any abnormality, you should consult a doctor in time to find out the cause. 1. Physiological factors: Fetal movement usually starts from the 7th week of pregnancy, and most mothers feel fetal movement in the 16th to 20th week of pregnancy. Fetal immobility may be due to the small gestation period or the thicker abdominal fat layer of the pregnant woman, so there is no obvious feeling of fetal movement. 2. Pathologic factors: (1) Fetal distress: fetal inactivity indicates a decrease in fetal movement. If the fetal movement is normally normal and suddenly appears to decrease, it may be caused by acute or chronic hypoxia in the uterus, and may even jeopardize health and life. (2) Umbilical cord around the neck: the umbilical cord is wrapped around the baby’s neck. When the umbilical cord is wrapped too tightly, the pulling of the umbilical cord can lead to the obstruction of blood circulation of the fetus, resulting in hypoxia, which can also lead to the decrease of fetal movement. If the fetal movement suddenly becomes abnormal, pregnant women should seek timely medical attention to find out the cause of the problem. In addition, pregnant women should monitor the fetal movement and the growth and development of the fetus through regular obstetric examinations during pregnancy.