Abnormalities 1)too much (polyhydramnios >1500ml Abnormal digestive system or CNS esophageal atresia(食管闭锁) anencephaly(无脑儿) 2)too little(oligohydramnios) <500m Abnormal urinary system poor development of kidney(肾脏发育不全) urethra atresia(尿道闭锁)• Abnormalities 1) too much (polyhydramnios) >1500 ml Abnormal digestive system or CNS - esophageal atresia(食管闭锁） - anencephaly（无脑儿） 2) too little (oligohydramnios) <500 ml Abnormal urinary system - poor development of kidney（肾脏发育不全） - urethra atresia（尿道闭锁）