If the hygiene hypothesis is correct, then month of birth/conception should have an effect on the risk of autism. Here is a report about a study which found tha

If the hygiene hypothesis is correct, then month of birth/conception should have an effect on the risk of autism. Here is a report about a study which found that autism is most likely in children conceived in winter: http://articles.latimes.com/2011/may/05/news/la-heb-autism-winter-conception-20110505 http://articles.latimes.com/2011/may/05/news/la-heb-autism-w.... There was another study which "debunks" the month of birth claim, but I cannot find a link to it.