Maternal use of folic acid supplements around the time of conception was associated with a lower risk of autistic disorder, the most severe form of autism spectrum disorders, in children, according to a Norwegian study published in the February 13 issue of JAMA.
"This finding does not establish a causal relation between folic acid use and autistic disorder, but provides a rationale for replicating the analyses in other study samples and further investigating genetic factors and other biologic mechanisms that may explain the inverse association," said Pål Surén, PhD, of the Norwegian Institute of Public Health in Oslo.
Dr. Surén and his colleagues used data from the Norwegian Mother and Child Cohort Study to examine a possible association between the supplements and risk of autism spectrum disorders. The study is a national registry of 109,020 children born between 1999 and 2009. The researchers assessed data concerning 85,176 children in the registry. At final follow-up, the subjects ranged in age from 3.3 to 10.2 (mean age, 6.4).
A total of 270 of these children (0.32%) had autism spectrum disorders: 0.13% had autistic disorder, 0.07% had Asperger’s syndrome, and 0.12% had pervasive developmental disorder not otherwise specified.
Approximately 33% of the mothers took folic acid supplements during the interval from four weeks before conception to eight weeks afterward. The investigators found an inverse association between the mother’s use of folic acid supplements periconceptually and the risk that the child would develop autistic disorder. Of the children whose mothers took the supplements, 0.10% developed autistic disorder, compared with 0.21% of children whose mothers did not.
Women who took folic acid supplements were more likely to have a college-level education, to have planned the pregnancy, to be nonsmokers, and to have a prepregnancy BMI less than 25 kg/m2, which are all possible confounders. To address this concern, the investigators assessed the use of fish oil supplements in the study sample. Use of fish oil supplements correlated with the same parental characteristics as did use of folic acid supplements, but not with the risk of autistic disorder. Similarly, the inverse association for folic acid use in the periconceptual period was not evident in mothers who only took the supplements later in pregnancy.
Surén P, Roth C, Bresnahan M, et al. Association between maternal use of folic acid supplements and risk of autism spectrum disorders in children. JAMA. 2013;309(6):570-577.