The weight range is 2.5-4kg, within this range is normal weight, basically no need to regulate. If the fetal weight is too low, you need to communicate with your doctor to find out the reason and terminate the pregnancy if necessary; if the fetal weight is too large, you need to pay attention to control the nutritional intake and increase the exercise to avoid obstructed labor due to oversized fetus. 39 weeks of fetal development standard body length is about 48-50cm, top-rump length is about 34-36cm, the fetus has been developed and mature, subcutaneous fat, pink skin, plantar skin has The fetus is mature, with a lot of subcutaneous fat, pink skin, skin on the soles of the feet, plump appearance, nails have reached the end of the fingers, female labia majora and minora are well developed, male testicles have descended into the scrotum. Precautions during pregnancy 1, if the fetus is too heavy in late pregnancy, it will affect the late production, usually should pay attention to diet regulation, light diet, appropriate food containing more protein and vitamins, control the amount of food, which is conducive to normal production; 2, late pregnancy need to perform ultrasound examination to understand the fetal condition, if necessary, regular weekly fetal heart monitoring, used to exclude the fetus intrauterine hypoxia, and ready to prepare for delivery; 3. 3. appropriate activities, such as walking, are needed in late pregnancy to promote labor initiation.