Information from the Baby Siblings Study about autism.
Baby sibs research has identified or confirmed several early warning signs, including lack of response to name, abnormal eye gaze and motor delays.
I do not know if my younger child has autism but I would say so far he does not exhibit these early warning signs whereas my older son with autism did.
This Autism Science Foundation podcast discusses the changes in autism brains, and in particular on this subject, differences between 3-5 months of age. The podcast also makes the point that autistic brains change over time so society needs to understand the needs of autistic people change over time. This should be obvious but there is so much misinformation out there, so repeating it.