In the 5th month of pregnancy, an amniotic fluid index of 8-18cm or an amniotic fluid depth of 3-7cm are considered normal amniotic fluid volume, but due to the different physical conditions of each person, the specific amniotic fluid volume also varies and needs to be combined with the fetal development to make a comprehensive judgment. The fetal kidneys have already excreted, and the urine excreted by the fetus is the main source of amniotic fluid. It mainly plays the role of protecting the fetus, maintaining the temperature of the uterine cavity and the balance of fetal body fluids, as well as buffering external pressure and assisting in labor. If the depth of amniotic fluid is >7cm in the second trimester, it is considered as excessive amniotic fluid, which is mainly caused by fetal malformation, gestational diabetes, twins or multiple births and maternal-fetal Rh blood group incompatibility. In mild cases of excessive amniotic fluid, no special treatment is needed. If the amniotic fluid is severe, the cause needs to be further defined by ultrasound and other examinations before treatment. When the depth of amniotic fluid is <3cm, it is considered as low amniotic fluid, mostly caused by amniotic membrane rupture, placental abruption, twin or multiple fetuses, fetal malformation and chronic hypertension and other disease factors. If the fetus is normal, the placental circulation can be improved by daily drinking and intravenous rehydration to increase the amount of amniotic fluid; if the fetus has abnormalities, it may be necessary to terminate the pregnancy. Therefore, it is recommended that pregnant women have regular ultrasound examinations to keep abreast of the status of fetal amniotic fluid. Pay attention to rest and exercise in moderation to prepare for a smooth delivery.