Normal range of amniotic fluid index

The normal range of the amniotic fluid index is an important indicator for assessing fetal development in the uterus. Generally, the normal range of the amniotic fluid index is considered to be 8–25 cm. This range is determined through ultrasound examination by dividing the area into four quadrants using the umbilical horizontal line and midline centered on the pregnant woman's umbilicus, and then summing the depths of amniotic fluid in these four quadrants. Specifically, if the amniotic fluid index is less than 8 cm, it is considered to be slightly low amniotic fluid; if less than 5 cm, it is defined as oligohydramnios (low amniotic fluid). Conversely, if the amniotic fluid index exceeds 25 cm, it is considered polyhydramnios (excessive amniotic fluid). Both polyhydramnios and oligohydramnios may adversely affect fetal growth and development. Therefore, pregnant women should undergo regular prenatal checkups during pregnancy to monitor changes in the amniotic fluid index and take appropriate measures under the guidance of a physician.