Fetal movement may be caused by physiological factors, hypoxia and trauma. 1. Physiological factors: pregnant women eating a lot of food, mental stress, overwork or loud sound stimulation, may lead to fetal movement suddenly especially active, usually will be improved by itself, the duration will not be too long, is a normal physiological phenomenon. 2. Hypoxia: when the fetus in the uterus lack of oxygen, will also lead to fetal movement suddenly especially active, usually with a variety of factors, such as fetal distress, placenta praevia, umbilical cord around the neck and so on. 3. Trauma: During pregnancy, improper care of the pregnant woman, the abdomen suffered a violent impact, can lead to fetal movement suddenly especially active, and in serious cases, can also cause miscarriage. In addition, fetal movement may also be related to fever, hypoglycemia and other factors, fetal movement is suddenly particularly active, and accompanied by other abnormalities, pregnant women are advised to seek timely medical examination and treatment.