It is normal to see a decrease in fetal movement during late pregnancy due to the fetal head being in the pelvis. At 39 weeks of gestation, all organs of the fetus are mature, but it is still growing, at this time the fetus weighs 3.3-3.4kg, the average biparietal diameter is 9.21±0.59cm, the body length is about 36cm from the head to the buttocks, the average abdominal circumference is 31.34±3.12cm, the femur length is 7.34±0.53cm, the fetal lungs are mature this week, the umbilical cord is about 51cm long. Fetal movement is an indicator to monitor the normal development of the fetus, the first fetal movement usually occurs around 18-20 weeks of gestation, but the magnitude is relatively small, at 32 weeks of gestation fetal movement is the most frequent, the number of fetal movement can be up to thousands of times a day, then the gestational weeks increase, the fetus gradually increases, in the uterus can move less and less space, so fetal movement will also gradually decrease. At 39 weeks of pregnancy, because the head of the fetus has been pelvic, fetal movement will be relatively less than in the middle, but it should be more than 30 times within 12 hours, if it is too little, the fetus may be at risk, and you should go to the hospital in time to perform fetal heart monitoring and, if necessary, ultrasound examination. The 39th week of pregnancy is the stage of fetal growth, its growth and development is very rapid, so pregnant women need to pay attention to a balanced diet, especially pay attention to supplement vitamins and calcium, iron and zinc and other nutrients to prevent vitamin deficiency and rickets. The decrease in fetal movement at 39 weeks must go to the hospital and pay attention to monitoring the fetal heart.