Hirschsprung's disease: This condition is characterized by the absence of ganglion cells in the distal bowel, leading to a functional obstruction. It is a common cause of intestinal obstruction in newborns, presenting with abdominal distension and failure to pass meconium within the first 48 hours of life.

Meconium ileus: This condition involves the obstruction of the small intestine due to impaction of meconium, often associated with cystic fibrosis. Newborns present with abdominal distension and failure to pass meconium.
Intestinal atresia or stenosis: These congenital anomalies involve a complete or partial obstruction of the intestinal lumen, leading to abdominal distension and failure to pass meconium.
Meconium plug syndrome: A condition where a plug of meconium obstructs the intestine, causing abdominal distension and failure to pass meconium.

Necrotizing enterocolitis: A serious condition involving infection and necrosis of the bowel, which can present with abdominal distension and failure to pass meconium. It is more common in premature infants but can occur in term infants as well.
Volvolus or intestinal malrotation: These conditions involve a twisting or abnormal rotation of the intestine, which can lead to obstruction and ischemia. They are surgical emergencies.
Hirschsprung's disease with enterocolitis: A complication of Hirschsprung's disease where the obstructed segment of bowel becomes infected, leading to a severe and potentially life-threatening condition.

Chronic intestinal pseudo-obstruction: A rare condition characterized by recurrent episodes of intestinal obstruction without any mechanical cause.
Congenital megacolon: A rare condition involving an abnormal dilatation of the colon, which can present with abdominal distension and failure to pass meconium.
Neonatal small left colon syndrome: A rare condition where the left colon is underdeveloped, leading to obstruction and abdominal distension.