The late stage of pregnancy refers to the period after 28 weeks of gestation. During this time, the fetus still requires a certain amount of amniotic fluid to maintain normal growth, development, and respiration. Generally, the amniotic fluid index (AFI) in the late stage of pregnancy tends to be slightly lower than in the mid-stage. First, between 28 to 36 weeks of pregnancy, which falls within the range of preterm labor, the amniotic fluid volume typically remains within the normal range. Specifically, the AFI should be between 80 to 180 millimeters. Second, after 37 weeks of pregnancy, the pregnancy is considered full-term. At this point, the amniotic fluid volume may decrease slightly, and the AFI can drop below the lower limit of the normal range. However, it should not be too low. Maintaining an AFI around 60, 70, or 80 millimeters is generally acceptable. If the AFI falls below 50 millimeters, it should be taken seriously as it indicates oligohydramnios (low amniotic fluid), and delivery should be expedited as soon as possible.