By UPTODATE:
Normal AFI: above 5 cm and below 24 cm - AFI of 5.1 to 8 cm has been termed borderline, but the clinical implications are unclear, and no strong evidence exists to support additional antenatal assessment of these pregnancies. We manage pregnancies with an AFI of 5.1 to 8 cm the same way as an AFI above 8 cm, without additional testing or hydration. Gestational age is not considered.