How do I stop my wife from worrying about whether or not our infant son has autism?0

We have an 8 year old, 5 year old, and 4 month old. All boys. The 8 year old is on the autism spectrum. He is high functioning and his teacher is confident he will test into the gifted program when they give the test this school year. He is extremely intelligent but struggles socially and emotionally. He is behind in maturity and has trouble making friends but other than that he seems like a perfectly normal kid.My 5 year old is not on the spectrum. My wife is so worried about the baby being on the spectrum. She believes the odds are higher than normal because of his gender (boys are more likely to be diagnosed on the spectrum) and the fact that we already have a child with autism (genetic link). She is a very smart and educated woman (works as a pharmacist) so I don't think she is buying into any propaganda surrounding autism but she spends a lot of time worrying about our youngest. She looks for early signs and any time he does something slightly off, she starts worrying about autism.I have brought up that worrying won't prevent him from being autistic. She knows that logically but can't apply it emotionally. I have suggested therapy or being looked at for PPD and she insist that she's fine. I don't know what else I can do. I don't want her obessing over this for years. via /r/Parenting https://ift.tt/2Pzjs8q