Spina bifida is a condition that is caused when one or more of the vertebrae in the spine fails to develop properly during the early stages of pregnancy.
There are three types of spina bifida, which are spina bifida cystica - comprising meningocele and myelomeningocele forms - and spina bifida occulta.
Myelomeningocele is the most serious form, affecting around one in 1000 babies. It manifests itself as a cyst or sac, covered in skin, that is usually visible on the back.
This sac contains tissues that cover the spinal cord. As a result, the spinal cord is either damaged or unable to develop properly. This usually results in paralysis and the inability to control the bladder.
Most children with myelomeningocele will also suffer from hydrocephalus, a condition that is caused when the fluid that surrounds the brain is unable to drain out. This leads to brain damage, which is exacerbated by the pressure from the fluid, and can cause the child's head to swell.
Spina bifida meningocele is a less serious condition, and happens when the cyst contains membranes. Nerve damage is usually minimal and disability is unlikely.
A person with spina bifida occulta is usually unaware of the condition, and it is very unlikely to cause disability.
Treatment for severe spina bifida comprises surgery to repair the spinal damage shortly after birth. Babies with hydrocephalus may have to have a shunt fitted, a device that drains fluid from the brain into the abdomen.
Taking a supplement of folic acid during the first 12 weeks of pregnancy is proven to prevent spina bifida from developing.