<prompt> All are causes of Polyhydramnios EXCEPT :Occult spina bifidaDiabetes mellitusSwallowing defects in fetusMultiple pregnancy  <response>: Polyhydramnios Causes: Diabetes Twin pregnancy Cleft lippalate Duodenal atresia Esophageal atresia Neural tube defects Gastroschisis Disorders such as duodenal atresia, esophageal atresia, gastroscisis and diaphragmatic hernia cause swallowing defects Open spina bifida causes polyhydramnios not occult spina bifida 