Neural tube defects (NTD's) are conditions where an opening in the spinal cord or brain remains from early in human development.

• In week 3 gestation, during gastrulation (i.e. phase where the single layered blastula is reorganized into a trilaminar structure called the gastrula), specialized cells on the dorsal/back of the fetus begin to change shape, and form the neural tube
• The failure of the neural tube to close completely is called an NTD

• Open, which is more common. It occur when the brain or spinal cord are exposed at birth through a defect in the skull or vertebrae (back bones), including:
  • Spina bifida, which affects the spine​
  • Anencephaly, which results in little to no brain
  • Encephaloceles, which affects the skull
  • Iniencephaly, which results in extreme bending of the head to the spine
  • Hydranencephaly, where the cerebral hemispheres are missing and instead filled with sacs of CSF
  • Schizencephaly
• Closed, which are rarer. It occurs when the spinal defect is covered by skin. It includes:
  • Lipomyelomeningocele
  • Lipomeningocele
  • Tethered cord

Source: 2059">NSW Health

• Prevention, with:
  • Folic acid supplementation, including enriched bread, cereals, flour, and other grain products

• One of the most common birth defects, affecting over 300k births each year worldwide
• Affects 0.035% of births, decreasing from 0.05% births since folate fortification was started