What is amniotic fluid depth? Amniotic fluid is the fluid that fills the amniotic cavity. The source of amniotic fluid: After mid-pregnancy, the main source of amniotic fluid is the fetal urine, the secondary source is the dialysis fluid formed by the blood of the pregnant woman through the amniotic membrane, and a small percentage can come from the fetal skin, lungs, umbilical cord and even the exudate from the surface of the placenta. When you have an ultrasound during pregnancy, the B-sheet will prompt information about the amniotic fluid. The terms amniotic fluid depth or amniotic fluid index are often written, but many pregnant women often confuse the two. The amniotic fluid depth and the amniotic fluid index are two different concepts. Amniotic fluid depth: The maximum vertical depth of the amniotic pool during an ultrasound examination during pregnancy is an important indicator used to determine how much amniotic fluid is present. Amniotic fluid depth standard: the normal amniotic fluid depth is in 3-7cm, if ≥8cm suggests too much amniotic fluid, if ≤2cm suggests too little amniotic fluid. Amniotic fluid index (AFI): The uterus is divided into four quadrants: upper left, upper right, lower left and lower right. The sum of the vertical depth of the maximum amniotic fluid dark area in the four quadrants is the AFI. The normal AFI is in the range of 8 – 18 cm, if ≥ 18 cm indicates that the amniotic fluid p is too much, greater than 24 cm indicates that the amniotic fluid is too much, if ≤ 8 cm indicates that the amniotic fluid is too little, and less than 5 cm indicates that the amniotic fluid is too little. Generally speaking, amniotic fluid depth between 3-7 cm is normal, more than 7 cm is increased amniotic fluid, and some people think it should be more than 8 cm before it is considered too much amniotic fluid or less than 3 cm is reduced amniotic fluid. Amniotic fluid index 8-20cm is normal amniotic fluid, when the amniotic fluid index is less than 5cm, it is too little amniotic fluid and the pregnancy should be terminated as soon as possible. The effect of amniotic fluid depth on the fetus: First, if the amniotic fluid is too much, look for the cause, such as high blood sugar, fetal malformation and other possible, look carefully for the cause, the perinatal morbidity and mortality rate is significantly higher in those with too much amniotic fluid. Second, if the amniotic fluid is too much, too little amniotic fluid in middle pregnancy suggests fetal developmental malformations, too little amniotic fluid in late pregnancy often leads to prolonged labor during delivery, and the fetus is prone to intrauterine asphyxia.