Low Maternal B12 Levels Affect Foetuses

Pregnant women with low levels of vitamin B12 have three times the risk of delivering babies with neural tube defects, according to a new study led by a University of Toronto researcher.

“In a population-based, case-control study of more than 500 pregnant women in Ontario, we found the risk of neural tube defects tripled in the presence of low maternal vitamin B12 levels,” said Joel Ray, a professor in the Department of Medicine and a St. Michael’s Hospital physician. “Taking into account folic acid fortification in flour and moderate use of folic acid supplements, the data suggest about 34 per cent of neural tube defects may be due to low levels of B12.”The study, published in the journal Epidemiology, is the first comprehensive study to examine the link between the two using an accurate measurement of vitamin B12 while adjusting for folate levels.Neural tube defects are birth defects of the spinal cord and brain, otherwise known as spina bifida and anencephaly. Research has shown the risk of neural tube defects can be reduced by nearly 50 per cent with folic acid supplements taken just before and after conception, or through consumption of food fortified with folic acid. However, an estimated six to 12 in every 10,000 foetuses in Canada still develop neural tube defects.The team measured levels of serum holotranscobalamin (holoTC), a sensitive indicator of vitamin B12 status, in more than 500 pregnant women at the 15 to 20 week gestation period. “The benefits of adding synthetic B12 to current recommendations for periconceptional folic acid tablet supplements or folic-acid-fortified foods needs to be considered,” the study concluded. “It remains to be determined what fraction of neural tube defect cases in a universally folate-fortified environment might be prevented by higher periconceptional intake of B12.”(Source: Epidemiology : University of Toronto : July 2007)