Background: To examine the prospective association between multivitamin supplementation during pregnancy and biomarker measures of maternal plasma folate and vitamin B 12 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 B 12 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 associated with increased risk of ASD. Very high levels of maternal plasma folate at birth (≥60.3 nmol/L) had 2.5 times increased risk of ASD [95% confidence interval (CI) 1.3, 4.6] compared to folate levels in the middle 80th percentile, after adjusting for covariates including MTHFR genotype. Similarly, very high B 12 (≥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 B 12 levels at birth were associated with ASD risk. This hypothesis-generating study does not question the importance of consuming adequate folic acid and vitamin B 12 during pregnancy; rather, raises new questions about the impact of extremely elevated levels of plasma folate and B 12 exposure in-utero on early brain development.

Little is known about the current practices of primary care physicians regarding developmental surveillance and screening during pediatric preventive care visits. We conducted a mailed survey of a random national sample of pediatricians and family physicians to describe their practices and identify factors that predict use of developmental screening tools, an efficacious way of identifying children with developmental delays. Most physicians reviewed developmental milestones and prompted parents for developmental concerns at preventive care visits. Approximately half of the physicians used a formal developmental screening instrument. Female physician gender predicted higher rates of use of screening tools for family physicians, but not for pediatricians. Most physicians seemed committed to the early diagnosis of developmental delays. Substantial variability in surveillance and screening practices, barriers of time and reimbursement, and under-reliance on parent-completed questionnaires underscore areas for improvement.