The placenta will gradually form during the eighth week of pregnancy, during which the amniotic fluid is slowly produced, and at the eleventh week of pregnancy, the fetal sac disappears completely and the placenta is basically formed. In the early stages, amniotic fluid is produced mainly through the epithelial secretion of the amniotic membrane and the transit of the amniotic membrane. The amniotic sac will begin to form on the eighth day after fertilization and amniotic fluid will be produced slowly at this time. The amniotic fluid is very important for the fetus, which will survive in the amniotic fluid and transport nutrients and oxygen supply through the placenta.