Amniotic fluid at 39 weeks of pregnancy is a manifestation of the decline in placental function, through a large number of drinking water and intravenous rehydration can not enhance the amount of amniotic fluid, because amniotic fluid is the formation of fetal urine, amniotic fluid after 39 weeks of pregnancy, the underlying cause of the low amniotic fluid lies in the placenta to supply blood, oxygen supply is reduced, the fetus’s urine production is reduced, and the amniotic fluid is also reduced. If the fetal movement is normal, electronic fetal heart monitoring is good, you can continue to observe, 3 days after the review ultrasound, amniotic fluid index is less than 50mm consider termination of pregnancy. If you are afraid that the amniotic fluid is too small to compress the umbilical cord or the contractions are not coordinated, you can inject warm saline into the amniotic cavity to induce labor, but this method is rarely used in the clinic. If you continue to review the ultrasound, the amniotic fluid index is between 50-80mm, you can continue to wait for delivery, closely observe the amniotic fluid, fetal movement and fetal heart, and terminate the pregnancy in time if you find any abnormality. If the amniotic fluid index is less than 50mm, termination of pregnancy is the key.