Question: Are parents who smoke more likely to have children with autism?
Answer: Smoking in itself is not known to directly cause autism. But, smoking causes metabolic changes in the body. In particular, it increases something called oxidative stress. And oxidative stress is something which we are finding at higher levels in people with autism. And oxidative stress is a risk factor for many diseases, not just autism -- such as obesity, diabetes, cancer and other things.
So smoking is not a good idea, and it could increase the background risk that would make a child more vulnerable to things which cause autism, because oxidative stress makes you more vulnerable to many things. So, it is not a good idea for this and many other reasons to smoke, and particularly not when you're pregnant or have a young child.