Please advise me. what do you think causes autism?

Multifactoral: Improved recognition is responsible for only part of the increase. Other theories are: our level of exposure to chemicals in our food and environment is thought to be a factor, and our increased consumption of processed food which often lack micronutrients are probably also at play. 1 reference about chemicals: http://www.Mheproducts.Com/autism/pfcs_and_autism.Htm.

Human variability: I suspect it's always been with us but is getting recognized more often. Whether a child is diagnosed as "austistic" or "retarded / learning disabled" varies tremendously place-to-place depending largely on how benefits work, and there's probably a spectrum between severe disability and mild geekiness. None of the "pop" claims have found any real scientific support so far

Autism: Truth is we do not know what causes autism. As time goes on pervasive developmental disorder is a spectrum of disorder ranging from mild to what we traditionally thought of as autistic children. The rise in incidence maybe some factor or may simple be our increasing awareness of it.