For example, it could be a congenital defect like spina bifida, or an acquired one like a skull fracture, where there might be CSF leaking through the sinuses.
A long-running project following 285,000 Chinese women, begun in 1983, helped demonstrate that folic acid could prevent spina bifida, a rare birth defect.
Other risk factors for having a child with spina bifida include obesity, poorly controlled diabetes, and taking medications that interfere with folate metabolism, like certain anti-seizure medications.
In spina bifida occulta, the spinal cord and surrounding tissue don't protrude, nor is any of the tissue forced into the spaces in between the vertebrae.
Now, the exact cause of all three types of spina bifida isn't known, but there are known risk factors like folate or Vitamin B9 deficiency during fetal development.
Women who do not get enough folic acid are at risk of giving birth to infants with part of their spinal cord or brain exposed. This disabling condition is called spina bifida.
This one's the least common form of spina bifida, and because the spinal cord itself is not damaged, these individuals often do not experience the severe symptoms that are seen in myelomeningocele.
In fact, occulta is latin for hidden, which is appropriate, since many of the normal prenatal tests used to diagnose spina bifida don't catch the disorder, because the deformities in the tissues of the lower back are tiny.