Constipation<unk> 
Congenital anorectal malformations
Imperforate anus
Bowel obstruction
Neurologic disorders
Encephalopathy
Spinal cord abnormalities: myelomeningocele, spina bifida, tethered cord
Meconium ileus
Cystic fibrosis
Metabolic causes
Hypothyroidism
Hypercalcemia
Hypokalemia
Diabetes insipidus
Heavy-metal poisoning 
Medication side effects
Imperforate anus
Cystic fibrosis
Hypothyroidism
Hypercalcemia
Hypokalemia
Diabetes insipidus
Hirschsprung's disease
Constipation
Meckel's diverticulum
Intussusception
Congenital anorectal malformations
Necrotizing enterocolitis
Imperforate anus
Duodenal atresia