Much has been learned about the causes of spina bifida, though there continues to be much that is not understood. Genetics appears to play a role since there is an increased risk of having a child with spina bifida if a sibling is affected.
Other risk factors have been identified though some are poorly understood. Women are at greater risk of having a child with spina bifida if they are from a low socioeconomic class, obese, have diabetes, take certain types of seizure medications during pregnancy (particularly valproic acid or carbamazepine), or exposed to high temperatures during the first trimester (either from an illness with fever or hot baths).
Race may play a role as well, with spina bifida occurring more in hispanics and whites of European descent. Folic acid supplementation prior to and during pregnancy has been found to reduce the risk of spina bifida, and the United States Public Health Service recommends a daily intake of 0.4 milligrams (400 micrograms) of folic acid for all women of childbearing age. Some studies suggest that women who have had children with neural tube defects or have a strong family history should take 4 milligrams of folic acid daily.
The brain and spinal cord of a fetus develop very early during pregnancy, with closure of the neural tube (tissues around the spine) by 28 days after conception. If closure has not occurred by that time, the result is a neural tube defect.
