The common causes of excessive amniotic fluid are as follows: 1, fetal digestive tract abnormalities: such as digestive tract obstruction; 2, fetal central nervous system abnormalities: such as cerebrospinal membrane bulging, bulging cerebrospinal membrane if more exudation, will lead to excessive amniotic fluid; 3, maternal blood sugar abnormalities: such as maternal gestational diabetes, the fetus in a high-sugar environment will occur osmotic diuresis, which leads to excessive amniotic fluid; 4, placenta, fetal membrane abnormalities: placenta, fetal membrane will produce a certain amount of amniotic fluid. If the placenta and fetal membranes have chorioamnion hemangioma, it will produce a large amount of amniotic fluid and lead to excessive amniotic fluid; 5, the fetus combined with chromosomal abnormalities: amniocentesis may be required to exclude fetal chromosomal abnormalities.