The amniotic fluid index in late pregnancy is usually between 8-25, and ultrasound examinations are reported to be normal. If it is between 5-8, it may be a critical amniotic fluid, or a suspected low amniotic fluid; if it is less than 5, it is considered to be too little amniotic fluid. If the amniotic fluid is relatively low and at a critical value, but the fetal movement is in the normal range and the fetal heart monitoring is good, the amniotic fluid can be replenished by drinking more water, and the change of amniotic fluid can also be monitored dynamically. Amniotic fluid index above 25 is considered excessive amniotic fluid, which is usually seen in fetal malformation, gestational diabetes, giant baby, etc. It will increase the probability of fetal malformation and baby hypoxia, and also increase the risk of premature rupture of membranes, placental abruption and umbilical cord prolapse. Amniotic fluid index less than 5 is considered as low amniotic fluid. Low amniotic fluid is usually associated with fetal malformation and baby hypoxia, as well as pregnancy complications, such as gestational diabetes, gestational hypertension and intrauterine growth restriction. Both of these conditions increase the risk to the mother and the fetus, so it is important to pay attention to any abnormalities in the amniotic fluid index during late pregnancy and to be hospitalized if necessary.