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Prenatal vitamins may lower risk of autism

June 3, 2011

Taking vitamins before and/or during the first month of pregnancy may reduce the chances of bearing a child with autism by 50 percent, says a new US study.

In the study, data from approximately 700 families with 2- to 5-year-old children who have autism or similar syndrome were collected (1). The women were asked whether they took prenatal vitamins containing folic acid and other B vitamins, multivitamins or other supplements at any time during the three months prior to and during their pregnancies and/or breastfeeding. Participants that had taken vitamins were asked what types they took, at what dosages and frequency, and during which months of pregnancy. The study results showed that women who reported not taking a daily prenatal vitamin immediately before and during the first month of pregnancy were nearly twice as likely to have a child with an autism spectrum disorder as women who did take the supplements. However, after the first month of pregnancy, there was no difference between mothers who did and did not take prenatal vitamins. According to the scientists, this indicates that by the time most women are aware that they are pregnant, taking prenatal supplements may not benefit the child in regard to risk of autism.

In addition, the study results suggested that consuming prenatal vitamins may be especially effective for genetically susceptible mothers and their children. For women with a particular high-risk genetic make up who reported not taking prenatal vitamins, the estimated risk of having a child with autism was as much as seven times greater than for women who reported taking prenatal vitamins and who had more favorable gene variants. The likelihood of bearing children with autism was significantly increased for mothers with two gene mutations leading to a less efficient folate metabolism and increased plasma levels of homocysteine.

The researchers commented that it is widely accepted that autism spectrum disorders are the result of multiple factors. Nevertheless, previous work on genes has generally ignored the possibility that genes may be activated by environmental factors.

Folate is known to be critical for neurodevelopment, and studies have found that supplemental folic acid has the potential to prevent up to 70 percent of neural tube defects.

References

  1. Schmidt R. J. et al. Prenatal vitamins, one-carbon metabolism gene variants, and risk for autism. Epidemiology. 2011.