At 18 weeks of pregnancy, the depth of amniotic fluid in the uterine cavity of a pregnant woman is about 3-8cm, which is normal. Each person’s physical condition is different, the growth and development of the fetus after pregnancy is different, and later the pregnant woman’s living environment and lifestyle are different, resulting in the amount of amniotic fluid in the uterine cavity of pregnant women is also different, some people are more, some people are less, but as long as it is within the normal value is normal. If the depth of amniotic fluid exceeds 8cm, it is considered too much amniotic fluid, which may be caused by abnormal fetal development, and it may also cause fetal cord prolapse or premature birth. If a pregnant woman is found to have too much amniotic fluid during an ultrasound, she needs to follow the doctor’s instructions for further examination to confirm whether the fetus has any developmental abnormalities, and if there are abnormalities, she should cooperate with the doctor to terminate the pregnancy as soon as possible. If the depth of amniotic fluid is less than 3cm in 18 weeks of pregnancy, it is considered as low amniotic fluid, which can easily lead to obstructed labor.