please drink plenty of fluids like butter milk, coconut water, juices at least 3-4 litres in a day to maintain normal afi levels.take care. If it is less then 5 cm it is less (known as oligohydramnios) and if it is more than 25 then it is known as polyhydramnios. An average AFI level is 80 mm to 140 mm when you are in your 20 weeks to 35 weeks of pregnancy. The AFI < 50-60 mm is assumed as oligohydramnios, while … Normal AFI varies from 80 mm to 180mm. Answer: Dear liquor means, amniotic fluid.when afi 8-18 is considered as normal or adequate.median afi level is approximately 14 from 20 -35 weeks, when the amniotic fluid begins to reduce in preparation for birth.when afi less than 5-6cm considered as oligohydramnios. After 35 week, AFI levels usually begin to reduce. Adequate fluid volume is detected by ultrasound, and the normal volume is indicated when the AFI (amniotic fluid index) is between 8 to 18 cm. 8 to 5 cm is borderline oligo, and 18 to 25 is borderline polyhydramnios.