The main causes of low amniotic fluid in mid-pregnancy are low water intake of the pregnant woman, hypovolemia of the mother, amniotic membrane pathology, abnormal placental function, etc. If there is no indication for termination of pregnancy, the fastest way to replenish the amount of amniotic fluid is amniotic cavity perfusion. If the amniotic fluid is found to be too low in the middle of pregnancy, there is no fetal abnormality after further examination, the pregnant woman has no special comorbidities, and there is no indication for termination of pregnancy, the amount of drinking water can be increased under the guidance of the doctor. The fastest way to replenish the amount of amniotic fluid is amniotic cavity infusion, i.e., through ultrasound-guided transabdominal puncture into the amniotic cavity to infuse fluids, which can quickly increase the amount of amniotic fluid. If low amniotic fluid is detected in mid-pregnancy, you should actively seek medical advice to find out the cause of low amniotic fluid and use appropriate treatment under the advice of your doctor.