Diet rich in folic acid greatly reduces defect's chances

Staff writerNovember 14, 2010 

Anencephaly is a rare birth defect that affects an estimated 859 U.S. babies each year, according to a recent study.

It occurs in the first 28 weeks of pregnancy, when the neural tube, which becomes the spinal column and brain, fails to close.

The tube starts out in the embryo as a sheet of cells that normally rolls into a cylinder. Anencephaly occurs when the "cephalic" or head end of the neural tube fails to close, resulting in the absence of a major portion of the brain, skull and scalp. If the bottom end of the tube fails to close, the defect is called spina bifida.

Infants with anencephaly usually have a brain stem, which controls reflex actions such as breathing. But they don't have a forebrain (the front part of the brain) or a cerebrum (the thinking part of the brain).

There is no cure or treatment for anencephaly. Infants often will be stillborn. If not, they usually die within hours after birth. They do not gain consciousness, and they are usually blind, deaf and unable to feel pain.

Unknown cause

The cause of anencephaly is unknown, but both genetics and environmental factors are thought to be involved.

In the 1990s, researchers learned that adding folic acid to women's diets could reduce the chances of neural tube defects by 70 percent.

That's why it's recommended that women of child-bearing age consume 400 micrograms of folic acid daily if they plan to have a child someday. It's possible to get that amount from an over-the-counter multivitamin. Folic acid also is present in leafy green vegetables and fortified pasta, bread and cereals.

Women who already have had a baby with a neural tube defect, or have a family history of the defect, are advised to get 10 times that amount - 4,000 micrograms - by taking prenatal vitamins.

At one point, North Carolina had one of the highest rates of neural tube defects in the world, according to Anna Bess Brown, program director for the N.C. March of Dimes.

Since 1995, when the state began an education campaign about the benefits of folic acid, neural tube defects in North Carolina have declined by 40 percent.

Education continues, especially among Hispanic women, who are at twice the risk of having babies with neural tube defects.

In the next year, Brown said a folic acid education campaign, paid for by a federal grant, will focus on Hispanic women in Mecklenburg County. (For information, call Leslie deRosset at 919-424-2149.)

Studying genetic links

Identifying genetic links is the goal of a study at Duke University Medical Center's Center for Human Genetics, where researchers are collecting the blood of parents and babies with anencephaly.

Shannon and Kip Brooks of Denver, N.C., are among the more than 300 families who enrolled in the project since 1993. Forty percent of enrollees have had two or more babies diagnosed with anencephaly in their families.

Choices about whether to have abortions or carry babies to term vary.

Findings from seven U.S. studies show wide-ranging results, depending on the number of families surveyed and their geographic location. For example, of 18 parents in an Atlanta-based study, 100 percent chose abortion. In the largest of the studies, half of the 285 parents surveyed in California chose abortion.

Of the Duke study families, about 50 percent chose to terminate their pregnancies, according to genetic counselor Heidi Cope.

"It's a very personal decision," said Allison Ashley-Koch, a genetic epidemiologist at Duke.

"For some families, perhaps they're just so devastated that termination seems like the best option. They think perhaps that's the more humane approach. Other families desire to carry the babies to term to have that closure, to hold the baby, even if the baby only survives a few minutes or a few hours."

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