Healthy development of the spinal column
Development of the spinal column starts very early during pregnancy. The brain, spinal cord and surrounding tissue develop from a structure called the neural tube. Usually, the neural tube is completely developed, or ‘closed’, between 26 and 28 days after the start of the pregnancy. Very rarely, the neural tube tears or fails to close.
What is spina bifida?
Spina bifida literally means ‘split spine’ or ‘open spine’ and is caused when the neural tube doesn’t close properly. This results in an incorrectly developed spine, so spina bifida is classified as a neural tube defect.
 | |  | Normal spine
| | Opening (Spina bifida)
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The specific features of spina bifida vary, but generally the small bones (vertebrae) that make up the spine don’t form fully and may have gaps between them. In severe cases, one or more vertebrae may be missing, exposing the spinal cord. In most spina bifida cases, the spinal defect is located towards the base of the spine.
Types of spina bifida
Spina bifida takes a number of different forms:
 | |  | |  | Occulta
The least serious and most common type, known as spina bifida occulta, is usually discovered only on x-rays or scans – and most people never become aware of their condition. | | Meningocele
In the next most serious type, meningocele the coverings of the spinal cord (meninges) pass back through the opening in the spine to form a cyst-like swelling. | | Myelomeningocele
If the spinal cord in enclosed in the cyst the condition is called myelomeningocele. This is the most serious type of spina bifida. |
How common is spina bifida?
Thankfully, spina bifida is a lot less common than it used to be, largely due to folic acid supplements taken by women around the time of conception and during the first 12 weeks of pregnancy. Although rates of spina bifida vary between countries, approximately 8 out of 10,000 live births are affected by spina bifida. Spina bifida tends to run in families – and if the first child has spina bifida meningocele or myelomeningocele, the risk to the second child rises to 5 percent; if two children have the condition, the risk to the third is 15 percent.
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