How much is the amniotic fluid index standard at 39 weeks of pregnancy?

Amniotic fluid volume will slowly increase after pregnancy, to 37 weeks to reach a peak, and then will slowly decline, 39 weeks of pregnancy is already the third trimester of pregnancy, this time fetal development has matured, amniotic fluid index should be between 8~18cm, amniotic fluid volume about 900 ml, if not within the range are amniotic fluid abnormalities.