The fetal kidney contributes increasingly to the amount of amniotic fluid from midpregnancy onwards. At term the fetal kidneys will be contributing about 500 ml per day. An estimate of liquor volume (though not accurate) can be achieved via ultrasound.
High levels of liquor are found in pregnancies affected by Rhesus disease. Very high levels of liquor occur in hydrops fetalis.
Amniotic volume may be reduced following amniocentesis - due to fluid leaking away. Other situations associated with low amniotic fluid volumes include pre-eclampsia and intrauterine growth retardation.