Amniotic fluid usually forms around 8-10 weeks of pregnancy. Usually, the placenta is formed at 8 weeks of gestation and amniotic fluid slowly appears during this process. In the early stages, the main source of amniotic fluid is maternal serum; in the second trimester, the main source of amniotic fluid is fetal urine; and in the late stages of pregnancy, fetal lungs will be involved in the production of amniotic fluid. The amount of amniotic fluid is relatively small at the beginning of the pregnancy, but as the weeks of pregnancy increase, the amniotic cavity gradually increases in size, and the amount of amniotic fluid will also gradually increase. Amniotic fluid is located in the amniotic cavity of the uterus and is one of the key elements in maintaining fetal growth and development. The amount of amniotic fluid can be used to determine the growth of the fetus in the uterus around 14-16 weeks of pregnancy. If the amount of amniotic fluid is too low, there may be intrauterine hypoxia of the fetus; if the amount of amniotic fluid is too high, it may lead to structural abnormalities of the fetus. If the amount of amniotic fluid is lower or higher than normal during pregnancy, it should be taken seriously and timely checked in the hospital for a clear diagnosis and early treatment to prevent the symptoms from worsening and affecting the growth of the fetus.