It is not normal for a fetus to move for three hours straight at 39 weeks of pregnancy. In late pregnancy, the fetus moves about 3-5 times per hour, and there will be small differences in the specifics depending on the individual circumstances of the pregnant woman. 1. persistent fetal movement: 3 hours of continuous fetal movement is a kind of persistent fetal movement, which means that the fetus may have the phenomenon of intrauterine oxygen deficiency. 2. Increased frequency of fetal movements: Fetal movements are more frequent than usual, which also means that the fetus may be suffering from intrauterine oxygen deprivation. 3. weakened frequency of fetal movement: the frequency of fetal movement is weaker than usual, which means that the condition of the fetus is more dangerous, not only intrauterine hypoxia, but also intrauterine asphyxia may have occurred. Fetal movement abnormalities should be the first time to consult a doctor, because fetal movement can not be used as an absolute judgment standard of intrauterine oxygen deficiency, but also combined with fetal heart rate monitoring and clinical ultrasound to further diagnose the state of the fetus at this time. If all other clinical indicators are normal except for the increased frequency of fetal movement, intrauterine hypoxia can be ruled out and observation is the main concern. If the situation is serious, it is necessary to take corresponding measures with the help of specialized doctors.