Maternal Vitamin D Levels During Pregnancy in Association With Autism Spectrum Disorders (ASD) or Intellectual Disability (ID) in Offspring; Exploring Non-linear Patterns and Demographic Sub-groups.
Low maternal vitamin D does not appear to cause autism or ID, so hold off on extra supplements for prevention.
01Research in Context
What this study did
Researchers looked at stored blood from pregnant women. They checked vitamin D levels during each trimester.
Later they saw which children got an autism or intellectual disability diagnosis. They asked whether low vitamin D raised risk.
What they found
Overall, low vitamin D did not increase the chance of autism or ID. The result was basically flat.
A tiny protective effect showed up only for non-Hispanic white moms and baby boys. The pattern looked like a shallow J-shape, not a straight line.
How this fits with other research
Kočovská et al. (2012) already warned that evidence linking vitamin D and autism was thin. The new data support that warning.
Whitehouse et al. (2013) saw weak links between low vitamin D and adult attention-switching problems. Green et al. (2020) now widen the lens and find no broad autism or ID risk, updating the picture.
Ali et al. (2019) also reported no link in a large preschool cohort. Together these studies form a row of zeros, making the vitamin D prevention story less likely.
Why it matters
BCBAs often field questions about vitamins. This paper gives you clear talking points: prenatal vitamin D deficiency is not a proven autism trigger. Counsel families to follow standard prenatal care, not special mega-doses. Save your energy for evidence-based interventions like early intensive ABA.
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02At a glance
03Original abstract
Increasing vitamin D deficiency and evidence for vitamin D's role in brain and immune function have recently led to studies of neurodevelopment; however, few are specific to autism spectrum disorder (ASD) and vitamin D in pregnancy, a likely susceptibility period. We examined this in a case-control study of 2000-2003 Southern Californian births; ASD and intellectual disability (ID) were identified through the Department of Developmental Services and controls from birth certificates (N = 534, 181, and 421, respectively, in this analysis). Total 25-Hydroxyvitamin D (25(OH)D) was measured in mid-pregnancy serum, categorized as deficient (<50 nmol/L), insufficient (50-74 nmol/L), or sufficient (≥75 nmol/L, referent category), and examined continuously (per 25 nmol/L). Crude and adjusted odds ratios (AORs) and 95% confidence intervals (95% CI) were calculated. Non-linearity was examined with cubic splines. AORs (95% CI) for ASD were 0.79 (0.49-1.3) for maternal deficiency (9.5%), 0.93 (0.68-1.3) for insufficiency (25.6%), and 0.95 (0.86, 1.05) for linear continuous 25(OH)D. Results were similarly null for ASD with or without ID, and ID only. Interactions were observed; non-Hispanic whites (NHW) (AOR = 0.82, 95% CI = 0.69-0.98) and males (AOR = 0.89, 95% CI = 0.80-0.99) had protective associations for ASD with continuous 25(OH)D. A positive association with ASD was observed in females (AOR = 1.40, 95% CI = 1.06-1.85). With splines, a non-linear inverted j-shaped pattern was seen overall (P = 0.009 for non-linearity), with the peak around 100 nmol/L; a non-linear pattern was not observed among NHW, females, nor for ID. Our findings from a large study of ASD and prenatal vitamin D levels indicate that further research is needed to investigate non-linear patterns and potentially vulnerable sub-groups. LAY SUMMARY: We studied whether mothers' vitamin D levels during pregnancy were related to their children having autism (or low IQ) later. Low vitamin D levels were not related to greater risk of autism or low IQ in children overall. With higher levels of mothers' vitamin D, risk of autism went down in boys, but went up in girls. Risk of autism also went down in children of non-Hispanic white mothers with higher vitamin D levels, but we did not find a relation in other race/ethnic groups.
Autism research : official journal of the International Society for Autism Research, 2020 · doi:10.1002/jbmr.3326