During pregnancy, if a woman has too little amniotic fluid, the amniotic fluid can be replenished by means of an infusion, which does not have a direct impact or harm on the fetal development. The amniotic fluid in the uterus during pregnancy must be within the normal range to ensure normal fetal development and normal activity, and the normal range of the amniotic fluid index is between 80-200mm. If the amniotic fluid index is less than 80mm or the maximum depth of amniotic fluid is less than 30mm during the ultrasound examination in the middle and late stages of pregnancy, the amniotic fluid is too small, which will have a great impact on the normal development and activities of the fetus. It can be improved by means of infusion. It is necessary to pay attention to the speed of infusion not to be too fast when supplementing amniotic fluid, to avoid the rapid increase of amniotic fluid in the uterus, which can be harmful to the fetus.