MONDAY, March 2 (HealthDay News) -- Women who do not have enough vitamin B12 in their blood before and after conception have a greater chance of having a baby with brain or spinal cord defects, a new study says.

Most at risk may be vegans and vegetarians, since B12 is far more common in meat and animal-based foods, noted an American and Irish research team whose findings were published in the March issue of Pediatrics..

According to the study, women with low levels of B12 had at least 2.5 times the risk of giving birth to a child with these neural tube defects, which can lead to partial paralysis or even death, than women with the highest B12 levels.

"Vitamin B12 is essential for the functioning of the nervous system and for the production of red blood cells," Dr. Duane Alexander, director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, said in a news release issued by its parent organization, the U.S. National Institutes of Health. "The results of this study suggest that women with low levels of B12 not only may risk health problems of their own, but also may increase the chance that their children may be born with a serious birth defect."

Researchers analyzed blood collected during the early pregnancy stages of hundreds of women from Ireland, a country with a high rate of neural tube defects. Either the women had previously given birth to a baby with a neural tube defect or were known to be carrying babies with the disorder.

Women with B12 concentrations below 250 ng/L before pregnancy had roughly three times the risk of having a child with a neural tube defect as those with higher B12 blood levels. Those women whose levels were less than 150 ng/L, which is considered B12 deficient, had five times the risk of women with higher levels.

The researchers used statistical techniques to focus solely on B12 levels and factor out the role of folic acid, a nutrient known to help prevent pregnant women from birthing babies with neural tube defects. The study authors noted that B12 and folate are jointly linked to several key biochemical reactions, but that a lack of either B12 or folate increased the risk of a neural tube defect.

While confirmation from other studies is needed, the authors suggested women should have vitamin B12 levels above 300 ng/L before becoming pregnant. Study co-author Dr. James L. Mills, a senior investigator in the NICHD division of epidemiology, statistics and prevention research, went further, recommending all women of childbearing age always consume the daily recommended amount of vitamin B12 and at least 400 micrograms of folic acid.

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