Folic Acid May Cut Autism Risk By Almost Half

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Women are told to take folic acid—even before they become pregnant—as a way to prevent neural tube defects in their babies. But should this advice be revised to also include reducing risk for autism? A new study from Norway says taking a folic acid supplement starting a month before pregnancy and continuing into the early first trimester may cut a child's chances of being diagnosed with autism by almost half.

As ABC New reports, Norwegian researchers followed over 85,000 babies born between 2002 and 2008 to determine whether or not folic acid supplementation during pregnancy had any effect on autism rates. Checking back in with the children and moms in 2012, researchers found that those women who took folic acid, beginning four weeks before they became pregnant and continuing until at least the eighth week of pregnancy, had a 40 percent lower risk of giving birth to a child later diagnosed with childhood autism (classic autism) compared to moms who didn't take a folic acid supplement during pregnancy.

What's so special about folic acid? The B vitamin is essential for the construction and repair of DNA molecules, the genetic material which controls all body cells, including brain cells. Getting enough folic acid during early pregnancy is now known to prevent neural tube defects in developing babies, including spina bifida. The March of Dimes recommends that all women of childbearing age get 400 micrograms of folic acid daily from a multivitamin. Pregnant women should continue taking 400 mcg of folic acid through early pregnancy as a way to prevent a deficiency.

"We know that folic acid deficiency leads to defects in the development of the nervous system [in the form of spina bifida and neural tube defects]," Dr. Ari Brown, a pediatrician in Texas, who was not involved in the study, tells ABC News. "So it would not be surprising that a deficiency might also affect brain development in other ways."

It's also important to note that it is folic acid, not folate, the unsynthesized form of the vitamin found abundantly in leafy green vegetables and other foods, that matters here.

"It appears that the reduced risk of childhood autism only reflects folic acid supplements, not food or other supplements...," Dr Pål Surén, primary author of the paper and researcher at the Norwegian Institute of Public Health, stresses in a statement.

Timing also matters. For example, the study found that—in terms of autism risk—folic acid supplements don't seem to have any impact past the 22nd week of pregnancy. As Surén adds, "the crucial time interval is from four weeks before conception to eight weeks into pregnancy." This is similar to the "critical window" for neural tube development.

With 1 out of 88 children now diagnosed with autism, according to Autism Speaks, this kind of news is encouraging, and let's hope further research will turn up even more about the connection between folic acid and autism.

But what if you're in your third trimester and are now worried because you didn't start taking folic acid until you found you were pregnant—or relied on vegetables in your diet to provide you with ample folate? Or what if you have a child with autism and can remember times you forgot to take your prenatal vitamin?

What has become clear in the past decade is that the cause of autism lies in a complex web of underlying genetic and environmental factors—there really is no one "smoking gun." And as Dr. Jennifer Ashton, a senior medical contributor to ABC News, explains, the message for all moms here should be: don't feel guilty.

"Society can sometimes do a really good job of laying blame and guilt, and when there is no medical proof that it is the mother's fault," she says.

"I usually tell women pregnancy is no different than parenting. There are never 100 percent guarantees of anything."