Polyhydramnios is a condition of excess accumulation of amniotic fluid beyond normal physiological function. Polyhydramnios poses many risks to mother and baby, in which the risk of premature birth in pregnant women with polyhydramnios at 35-36 weeks is many times higher than in pregnant women with normal amniotic fluid.

Almost every pregnant woman is asked to measure the AFI index - amniotic fluid index - when going for a prenatal check-up to monitor the amount of amniotic fluid, to prevent cases of insufficient or excess amniotic fluid during pregnancy. In particular, the condition of excess amniotic fluid at 31 weeks of pregnancy or excess amniotic fluid at 32 weeks, excess amniotic fluid at 35 weeks all have more or less impact on the fetus and mother.