The Association of Prenatal Vitamins and Folic Acid Supplement Intake with Odds of Autism Spectrum Disorder in a High-Risk Sibling Cohort, the Early Autism Risk Longitudinal Investigation (EARLI).
Katharine K Brieger, Kelly M Bakulski, Celeste L Pearce and 8 others
PMID 34110557WHAT IT FOUND
Taking prenatal vitamins in the first month of pregnancy did not significantly lower the odds of autism in high-risk siblings.
The study was too small to rule out a benefit, so clinicians should continue recommending standard prenatal care.
Key findings
01Prenatal vitamin use in the first month of pregnancy was not associated with reduced odds of ASD in the child.
02High folic acid intake (>1000 mcg) in the first month was not associated with odds of ASD compared to adequate intake.
03Mothers of children who developed ASD were consistently less likely to be taking prenatal vitamins throughout pregnancy, though this trend was not statistically significant.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The sample size was modest (191 pairs), which limited the precision of the effect estimates and resulted in wide confidence intervals. The study only examined high-risk families (siblings of children with ASD), so findings may not apply to the general population. Data on very early life interventions before age 3 was not available, which could be a confounder. Residual confounding is possible, as prenatal vitamin use is often associated with other healthy behaviors not fully captured or controlled for.
The easy way to misread this
Do not interpret the lack of a statistically significant association as evidence that prenatal vitamins do not help prevent ASD recurrence. The study was underpowered, and the confidence intervals were wide enough to include a clinically meaningful protective effect consistent with prior research.