What is amniotic fluid and how much amniotic fluid is normal during pregnancy? Amniotic fluid during pregnancy is the fluid between the amniotic membrane of a pregnant woman and the fetus. Under normal circumstances, the amount of amniotic fluid will gradually increase and reach its maximum level in the third trimester of pregnancy. In the early stages of pregnancy, the amount of amniotic fluid is small, only about 50-100 ml. In the second trimester of pregnancy, the amount of amniotic fluid will increase to 500-800 ml. In the third trimester, the amount of amniotic fluid will increase even more.