Prenatal folic acid may lower risk of autism

A study by Norwegian researchers has shown that the use of folic acid supplements around the time of conception may lower the risk of autism in children. The study was published in the Feb. 13 issue of JAMA.

The study looked at 85,176 children in the Norwegian Mother and Child Cohort Study (MoBa). The children were born between 2002 and 2008. By the end of follow-up on March 31, 2012, the children were aged 3.3 years through 10.2 years (mean, 6.4 years). The researchers examined the mothers’ use of folic acid from 4 weeks before to 8 weeks after the start of pregnancy, defined as the first day of the last menstrual period before conception.

At the end of the follow-up period, 270 children in the study sample had been diagnosed with autism spectrum disorders: 114 with autistic disorder, 56 with Asperger syndrome, and 100 with pervasive developmental disorder–not otherwise specified (PDD-NOS). In children whose mothers took folic acid, 0.10% had autistic disorder, compared with 0.21% in those whose mothers had not taken folic acid. The adjusted odds ratio for autistic disorder in children of folic acid users was 0.61 (95% CI, 0.41-0.90).

No association was found with Asperger syndrome or PDD-NOS.

The researchers noted that “women who used folic acid within the exposure interval … were more likely to have college- or university-level education, to have planned the pregnancy, to be nonsmokers, to have prepregnancy body mass index below 25, and to be first-time mothers. Folic acid use increased substantially by year of birth, from 43.2% in 2002 to 83.7% in 2008.”