Children born to women who had low levels of vitamin B12 in their blood shortly before and after conception may have an increased risk of a neural tube defect, according to the Irish National Institutes of Health. It has been documented that women with the low B12 levels are five times more likely to have a child with a neural tube defect than women with the higher B12 levels.

Women who consume little or no meat or animal-based foods are the most likely group of women to have low B12 levels, along with women who have intestinal disorders that prevent them from absorbing sufficient amounts of the vitamin.

Neural tube defects are a class of birth defects affecting the brain and spinal cord. One type, spina bifida, can cause partial paralysis, and is the country’s most common, permanently disabling birth defect, according to the Spina Bifida Association. These kinds of defects occur in 7 out of every 10,000 live births in the United States. October is National Spina Bifida Awareness Month.

Researchers have known that taking folic acid prior to and after conception can greatly reduce a woman’s chances of having a child with spina bifida or another neural tube defect. Folic acid is the synthetic form of the B vitamin folate. In addition to folic acid, vitamin B12 is also now believed to play a large role in the prevention of neural tube defects. Vitamin B12 is essential for the functioning of the nervous system and for the production of red blood cells.

To date, it is not known exactly how B12 and folate interact to influence the formation of the neural tube structure that gives rise to the spine and brain. Researchers have noted that the two vitamins are jointly involved with several key biochemical reactions, as well as with the synthesis of DNA. Lack of either vitamin B12 or folate in any of these chemical processes theoretically could increase the risk of a neural tube defect.

Although this subject still requires further research among other populations of women, researchers in Ireland are now recommending that women should have vitamin B12 levels above 300 ng/L before becoming pregnant.
 
Since vitamin B12 comes from foods of animal origin, women who are strict vegetarians may be at risk for a deficiency. In fact, it is wise for all women of childbearing age to consume the recommended amount of vitamin B12, whether they are planning a pregnancy or not.

Vitamin B12 is available in milk, meats, poultry and eggs, as well as fortified cereals and some other fortified foods. Information on foods that contain vitamin B12, as well as the recommended dietary allowances (RDA) for the vitamin, is available from the NIH Office of Dietary Supplements,  http://dietary-supplements.info.nih.gov/factsheets/vitaminb12.asp