When a woman is 20 weeks pregnant, it is normal if the maximum depth of amniotic fluid is 3.6cm. Amniotic fluid can provide space for the growth and development of the fetus and can play a buffering role to prevent the fetus from external stimulation. The normal range of the maximum depth of amniotic fluid at 20 weeks of pregnancy is between 3 and 8cm, and if the depth of the amniotic fluid is 3.6cm at this time, it belongs to the normal range and there is no need to intervene excessively. It is recommended that women during pregnancy actively pay attention to their own physical status, regularly complete fetal heart rate monitoring, Down syndrome screening and other tests to determine whether the growth and development of the fetus is in the normal range, if the body during pregnancy symptoms, it is recommended to go to the hospital in a timely manner, under the guidance of the doctor to carry out standardized treatment, to promote the alleviation of the condition.