Birth Defects Linked to Low Vitamin B12
Study Shows B12 Deficiency May Raise Risk of Spina Bifida and Other Neural Tube Defects
WebMD News Archive
March 2, 2009 -- Women who don't get enough vitamin B12 may have a higher
risk of giving birth to a baby with a potentially disabling or fatal birth
A new study shows that women with vitamin B12 deficiency in early pregnancy were up to five times more likely to have a
child with neural tube defects, such as spina
bifida, compared to women with high levels of vitamin B12.
"Vitamin B12 is essential for the functioning of the nervous system and
for the production of red blood cells," says Duane Alexander, MD, director
of the National Institute of Child Health and Human Development, which funded
the study. "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
Researchers say the results suggest that women of childbearing age, women in
early pregnancy, and women who hope to become pregnant should take steps to
ensure their diet includes foods rich in vitamin B12 or take supplements to
reduce their risk of vitamin B12 deficiency and birth defects.
Vitamin B12 is found in meat, poultry, milk, eggs, and other fortified
foods. Vegans and vegetarians, and women who have intestinal disorders that
prevent them from absorbing vitamin B12, are most susceptible to vitamin B12
deficiency. Vegetarian sources of vitamin B12 include fortified breakfast
cereals and some fortified vegetarian "meat" products like veggie
Vitamin B 12 and Pregnancy
Neural tube defects refer to a group of birth defects that affect the brain
and spinal cord. The defects include spina bifida, which can cause partial
paralysis, and anencephaly, a fatal condition in which the brain and
skull are severely underdeveloped.
The synthetic form of the vitamin folate,
folic acid, can significantly reduce the risk of neural tube defects. With
food fortification, the incidence of neural tube defects has decreased
dramatically. Researchers say these results suggest it may also play a role in
birth defect prevention.
In the study, published in Pediatrics, researchers compared vitamin
B12 levels in blood samples taken from three groups of Irish women between 1983
and 1990 who were pregnant with or previously had a child with a neural tube
defect to those in women with healthy pregnancies. The researchers took into
account folate levels in their analysis.
In all three groups, women with low vitamin B12 levels (below 250 ng/L) were
up to three times more likely to have a child with a neural tube defect than
those with higher levels. Women with vitamin B12 deficiency (levels below 150
ng/L) had the highest risk -- five times higher than that of women with higher
levels (greater than 400 ng/L).
Researchers say further studies are needed to confirm these results, but the
findings suggest that having vitamin B12 levels above 300 ng/L before becoming
pregnant may reduce a child's risk of birth defects.