Prenatal folic acid supplements reduce the risk of neural tube defects in children, but it has not been determined whether they protect against other neurodevelopmental disorders.
To examine the association between maternal use of prenatal folic acid supplements and the subsequent risk of autistic disorder in children.
Design, Setting, and Patients
The study sample of 85,176 was derived from the population-based, prospective Norwegian Mother and Child Cohort Study (MoBa). The children were born in 2002–08. By the end of follow-up on March 31st, 2012, the age range was 3.3–10.2 years and the mean age 6.4 years. The exposure of primary interest was use of folic acid from 4 weeks before to 8 weeks after the start of pregnancy. The start of pregnancy was defined as the first day of the last menstrual period before conception. Relative risks of ASD were estimated by odds ratios (ORs) with 95% confidence intervals (CIs) in a logistic regression analysis. Analyses were adjusted for maternal education level, year of birth, and parity.
Main Outcome Measure
Specialist-confirmed diagnosis of autistic disorder.
To date, 114 children in the study sample have been diagnosed with autistic disorder. In children whose mothers took folic acid, 0.10% (64/61,042) had autistic disorder, compared with 0.21% (50/24,134) in those unexposed to folic acid. The adjusted OR for autistic disorder in children of folic acid users was 0.61 (95% CI, 0.41–0.90). Similar analyses for prenatal fish oil supplements showed no such association with autistic disorder, even though fish oil use was associated with the same maternal characteristics as folic acid use.
Prenatal folic acid supplements around the time of conception were associated with a lower risk of autistic disorder in the MoBa cohort.