The Full form of AFI is Amniotic Fluid Index. AFI is an ultrasound procedure used to assess the amount of amniotic fluid. The amniotic fluid index is measured by dividing the uterus into four imaginary quadrants. The linea nigra is used to divide the uterus into left and right halves. The umbilicus serves as the dividing point for the lower and upper halves. Amniotic Fluid Index is a quantitative estimate of amniotic fluid and an indicator of fetal well-being. It is a part of the biophysical profile. An AFI between eight to eighteen is considered normal. Median AFI level is approximately fourteen from week twenty to week thirty five, when the amniotic fluid begins to reduce in preparation for birth. An AFI less than five to six is considered as Oligohydramnios. The exact number can vary by gestational age. The fifth percentile for gestational age is sometimes used as a cutoff value. An AFI more than twenty four to twenty five is considered as polyhydramnios. The causes of low amniotic fluid are due to leaking or rupture of membranes, placental problems, birth defects or maternal complications. Drinking water helps your body fight off painful urinary tract infections.