Maternal multivitamin intake, plasma folate and vitamin B12 levels and Autism Spectrum Disorder risk in offspring

Maternal multivitamin intake, plasma folate and vitamin B12levels and Autism Spectrum Disorder risk in  offspring

Abstract
Background—To examine the prospective association between multivitamin supplementation
during pregnancy and biomarker measures of maternal plasma folate and vitamin B12 levels at
birth and child's Autism Spectrum Disorder (ASD) risk.

Methods—This report included 1257 mother-child pairs, who were recruited at birth and
prospectively followed through childhood at the Boston Medical Center. ASD was defined from
diagnostic codes in electronic medical records. Maternal multivitamin supplementation was
assessed via questionnaire interview; maternal plasma folate and B12 were measured from samples
taken 2-3 days after birth.

Results—Moderate (3-5 times/week) self-reported supplementation during pregnancy was
associated with decreased risk of ASD, consistent with previous findings. Using this as the reference group, low (≤2 times/week) and high (>5 times/week) supplementation was associatedwith increased risk of ASD. Very high levels of maternal plasma folate at birth (≥60.3 nmol/L) had2.5 times increased risk of ASD (95% confidence interval [CI] 1.3, 4.6) compared to folate levelsin the middle 80th percentile, after adjusting for covariates including MTHFR genotype. Similarly,very high B12 (≥536.8 pmol/L) showed 2.5 times increased risk (95% CI 1.4, 4.5).

Conclusion—There was a “U” shaped relationship between maternal multivitamin

supplementation frequency and ASD risk. Extremely high maternal plasma folate and B12 levels at

birth were associated with ASD risk. This hypothesis-generating study does not question the

importance of consuming adequate folic acid and vitamin B12 during pregnancy; rather, raises new

questions about the impact of extremely elevated levels of plasma folate and B12 exposure in-utero

on early brain development.

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