Folic Acid Overuse During Pregnancy May Increase Autism Risk: Study

While health experts often recommend pregnant women take folic acid to protect their infants from birth defects, the findings of a new study suggest that if women take too much folic acid during pregnancy it may actually increase the risk of autism for the child. 

In a study presented Friday at the International Meeting for Autism Research in Baltimore, researchers from the Johns Hopkins Bloomberg School of Public Health found that women who had high levels of folate, vitamin B9, or vitamin B12 in their blood were twice as likely to have a child with autism. The findings raise concern, but are still considered preliminary, as they have not yet been published in a peer reviewed medical journal.

The study involved an analysis of data from nearly 1,400 pregnant women and their children in the Boston Birth Cohort, a predominantly low-income minority population. The mothers were included into the study at the time of their children’s birth between 1998 and 2013. The mother’s blood folate levels were checked within three days of delivery and they were followed for several years.

One in 10 of the women had what is considered an excess amount of folate, while six percent had an excess amount of vitamin B12 in their systems at delivery.

Mothers who had very high blood levels of folate at delivery were twice as likely to have a child with autism compared to mothers with normal folate levels. Mothers with excessive B12 levels were three times as likely to have a child with autism.

Folic acid is used by pregnant women to help protect infants from birth defects of the brain and spinal cord, including neural tube defects and spina bifida. In 2014, the CDC highlighted the risks and costs associated with birth defects in the U.S., recommending folic acid supplements during pregnancy as a prevention method, as do many doctors and health officials.

Researchers indicate the that the autism risk was 17 times higher for women with high levels of folate and vitamin B12. They emphasized there was an association between high levels of the two nutrients and autism, but could not prove the high levels caused an increased risk of autism.

Despite the risk of associated with very high doses, researchers also concluded women who took folate and B12 supplements three to five times per week were less likely overall to have a child with autism.

Folic Acid Used To Prevent Birth Defects

Folic acid supplementation is important and researchers don’t want people to stop taking their vitamin supplements if they are trying to get pregnant or are already pregnant.

A CDC report last year revealed 28 percent fewer women were giving birth to children with neural tube defects, an improvement health officials attribute to increased use of folic acid supplements during pregnancy.

The difficult task for researchers now is to determine the optimal dose of folate for pregnant women. Some folate is helpful and can protect the baby, too much can cause other problems.

However, some women may just be more genetically disposed to high levels of folate and B12 in the body, or they may be getting too much through their diet and supplements. Many women in the study said they took folic acid supplements. Folate is also naturally occurring in fruits and vegetables and it is used to fortify cereals and breads in the U.S.

The March of Dimes, the American College of Obstetricians and Gynecologists and other medical associations recommend pregnant women take folic acid to prevent Spina Bifida, the most common type of birth defect, and neural tube defects, which occurs in about 3,000 pregnancies each year in the U.S.

Women concerned about the findings of the study should talk to their doctor about their diet and supplements they are currently taking and how those things may affect blood levels of folate and B12.