31 weeks pregnant left side sleep fetal movement may be normal, without special treatment, may also be due to a variety of reasons caused by intrauterine hypoxia of the fetus, can be dealt with by changing the sleeping position, oxygen, timely intervention and other ways of treatment. 31 weeks pregnant fetus has become mature, fetal movement power is greater than before, the left side of the sleep may appear frequent fetal movement phenomenon, if the total number of self-counting fetal movement is not obvious increase or decrease, generally no special treatment. If the left side of the 31 weeks of pregnancy to sleep the fetal movement is strong if the duration is longer, may be the fetus in the uterus is compressed, this time to change the posture of lying down, change to the right side of the lying down position or appropriate standing and walking, to see whether the number of fetal movement will return to normal. The left side of the 31 weeks of pregnancy sleep fetal movement may also be caused by fetal intrauterine hypoxia, if the fetal movement is frequent and powerful can not be relieved, it is recommended to go to the hospital to do ultrasound to understand the situation of the fetus in the uterus, and if necessary, appropriate oxygen, to improve the hypoxia state. In addition to oxygen therapy, further treatment should be considered according to the severity of hypoxia. Fetal movement is recommended to go to the hospital to find the cause, and then targeted treatment.