A quarterly publication of the Autism Research Institute
Fall, 2016 | Number 4, Volume 30
Autism rates are highest among children conceived in the winter months, according to a large-scale study conducted in Scotland.
D. F. Mackay and colleagues analyzed data on more than 800,000 children, comparing those with and without an autism diagnosis. They found that rates of autism were highest among children conceived between January and March, and lowest among children conceived between July and September. They add, “Seasonal variations were specific to autism spectrum disorder, intellectual disabilities, and learning difficulties (e.g., dyslexia) and were absent for sensory or motor/ physical impairments and mental, physical, or communication problems.” Overall, they say, seasonality accounted for 11.4% of all cases of autism, intellectual disability, and learning difficulty.
The researchers say that low vitamin D levels during the winter may help to explain their findings. In addition, they say, high rates of influenza during the winter months may play a role.
“Month of conception and learning disabilities: a record-linkage study of 801,592 children,” D. F. Mackay, G. C. Smith, S. A. Cooper, R. Wood, A. King, D. N. Clark, and J. P. Pell, American Journal of Epidemiology, October 1, 2016 (epub prior to print publication). Address: Jill Pell, [email protected].
