What is the normal range for amniotic fluid index in late pregnancy?
Apr 26, 2023
Source: Cainiu Health
Dr. Lv Aiming
Introduction
In the late stages of pregnancy, the normal range for the amniotic fluid index (AFI) is 8 to 25 centimeters. The AFI is measured during an ultrasound by dividing the uterine area into four quadrants—upper, lower, left, and right—centered on the mother's umbilicus. The sum of the amniotic fluid depths in these four quadrants gives the amniotic fluid index. In late pregnancy, the fetus still requires an adequate amount of amniotic fluid to support normal development and lung maturation. Both excessive and insufficient amniotic fluid levels are harmful to the fetus.
Under normal circumstances, in the late stages of pregnancy, the normal range for the amniotic fluid index (AFI) is 8 to 25 centimeters. The amniotic fluid index is determined during an ultrasound by dividing the uterine cavity into four quadrants—upper, lower, left, and right—with the pregnant woman's navel as the center point. The sum of the deepest vertical pockets of amniotic fluid in each quadrant gives the amniotic fluid index. Specific analysis is as follows:
The amniotic fluid index increases with gestational age and begins to gradually decrease during the final 2–4 weeks of pregnancy. At term, the average amniotic fluid index is approximately 10 centimeters. An AFI greater than 25 centimeters in late pregnancy is diagnosed as polyhydramnios (excessive amniotic fluid), which is most often idiopathic but may be associated with fetal neurological developmental abnormalities or gastrointestinal obstruction. If the amniotic fluid index is less than 8 centimeters during late pregnancy, it is diagnosed as oligohydramnios (low amniotic fluid). The most common cause is decreased placental function. Drinking large amounts of soy milk or nutritious soups may effectively enhance placental metabolism and improve oligohydramnios. However, if symptoms do not improve, delivery should be initiated promptly under medical guidance.
In late pregnancy, the fetus still requires an adequate amount of amniotic fluid to support normal development and lung maturation. Both excessive and insufficient amniotic fluid levels are detrimental to the fetus. Therefore, under medical supervision, it is essential to identify the underlying cause and provide targeted, symptomatic treatment.
