我后来查了一下，公众意识和检查的标准变化是主要原因。 比例跟以前应该差不多，看到一个自闭症的专家也是这么说。

https://www.scientificamerican.com/article/the-real-reasons-autism-rates-are-up-in-the-u-s/

 

Is there no real increase in autism rates, then?
Awareness and changing criteria probably account for the bulk of the rise in prevalence, but biological factors might also contribute, says Durkin. For example, having older parents, particularly an older father, may boost the risk of autism. Children born prematurely also are at increased risk of autism, and more premature infants survive now than ever before.