akuperma – two others I have read about are ultrasounds and genetic modifications of foods.
I must throw in as my own two cents, however, that with all I have learned, seen and experienced of autism, if I had to pick something as a cause (which i don’t)I personally would put my money on something food-based. Seeing the types of problems they suffer from (gastrointestinally) and the behaviors they display, and seeing what food sensitivities have sparked in many people, it is probably the closest relationship of all the correlated things i have seen.