Amniotic fluid index of 200mm at 28 weeks is normal. Amniotic fluid index ≥250mm is too much amniotic fluid, ≤50mm is too little amniotic fluid, amniotic fluid specifically protects the fetus from extrusion, and at the same time reduces the discomfort caused by fetal movement to the pregnant woman. The production and absorption of amniotic fluid in normal pregnancy is in dynamic balance, and the main sources of amniotic fluid after 20 weeks are fetal urination and secretion of lung fluid. Pregnant women with excessive amniotic fluid need to rule out the presence of fetal developmental abnormalities, especially fetal chromosomal abnormalities, neural tube and digestive tract malformations. Low amniotic fluid needs to exclude whether the fetus has abnormal development of the urinary system, and there are also some amniotic fluid excess or low amniotic fluid of unknown cause, called idiopathic amniotic fluid excess or low amniotic fluid. During pregnancy, you should have regular checkups under the guidance of a specialized doctor, pay attention to the condition of the fetus, the placenta and the amount of amniotic fluid, and deal with any abnormalities promptly.