Polyhydramnios is defined as an excessive amount of amniotic fluid over 2000 ml and occurs in about 1 in 200 pregnancies. Oligohydramnios is defined as a decreased amount of amniotic fluid and can be caused by fetal abnormalities, premature rupture of membranes, or maternal conditions like diabetes. Together these conditions involve abnormalities in the normal amount of amniotic fluid surrounding the fetus.