What is spina bifida?

Spina bifida is a birth defect in which the bones of the spine (vertebrae) do not form properly around the spinal cord. This can occur anywhere along the spine. Spina bifida is the most common of a group of birth defects called neural tube defects.

Spina bifida develops in a fetus early in pregnancy, often before a woman knows she is pregnant. In the United States, over 4 million babies are born each year, and 1,500 to 2,000 of these have some form of spina bifida.¹ It is one of the most common birth defects, although the rates have steadily declined in recent years.

There are two main types of spina bifida: spina bifida occulta and spina bifida manifesta.

• Spina bifida occulta is the mildest and most common form. The spinal defect is hidden under the skin and does not usually cause problems or need treatment. Doctors estimate that up to 24% of the general population unknowingly have this spinal defect.² In some cases, a dimple, depression, birthmark, or hairy patch forms over the skin where more than one vertebra is affected. This is referred to as occult spinal dysraphism (OSD).
• Spina bifida manifesta is the rare form of this birth defect. It can be separated into two classes, meningocele and myelomeningocele.
  • In meningocele, fluid leaks out of the spinal canal, causing a swollen area over the baby's spine. In many cases, meningocele causes no symptoms.
  • Myelomeningocele is the most rare and severe form of spina bifida. This is the form most people mean when they say "spina bifida." In myelomeningocele (also called meningomyelocele), a segment of the spinal nerves pushes out of the spinal canal against the underside of the skin. The nerves are often damaged. In the worst cases, the skin is open and the nerves are exposed to the outside of the body. Meningomyelocele is often associated with nerve damage that can result in problems with walking, bladder control, and coordination.

What causes spina bifida?

Doctors do not know the exact cause of spina bifida but believe that both genetic and environmental factors are involved. Women who have had one child with spina bifida are more likely to have another child with spina bifida. Other factors that may increase the risk for having a baby with spina bifida include:³

• Having folic acid deficiency.
• Taking certain medicines, such as some used to treat epilepsy or acne.
• Excessive use of alcohol.
• Exposure to certain chemicals.
• Exposure to high temperatures.
• Having diabetes.
• Being obese.

What are the symptoms?

Symptoms of spina bifida depend on the severity of the condition. In spina bifida occulta, there may be no symptoms or only a dimple, depression, birthmark, or hairy patch over the affected vertebrae.