No one knows what causes autism. In light of this, what is a concerned parent to do? Having had one child with autism, I've had cause to think about this, and my opinion is -- everything! Some of the following are things research suggests may help; others are just common sense. I believe the prudent thing is to do all of them.

Starting before conception:

• Both parents should eat lots of fish.
• the mother should take pre-natal vitamins
• Be careful about both parents' reproductive health, especially the mother's.

During pregnancy:

• The mother should continue to eat lots of fish, take pre-natal vitamins, and, if any type of inflammation or other complication should develop, get it treated as quickly and aggressively as possible.

After birth:

• Play with the child a lot. Obviously any child needs a lot of human contact, but it is doubly important for autism prevention. Both human contact in general, and eye contact in particular, are critical! I would suggest a minimum of mechanical toys for entertainment in the first few months. The entertainment should come from people!
• Carrying the child in a baby backpack or sling is likely much better than a stroller (other than the first couple of months, when the baby doesn't yet know how to hold its head).
• Eye contact is just common sense -- it is one of the first issues in treating autism. Therefore, establishing it is likely to help prevent autism from developing, and to make it less serious if it does.
• About the whole debate on whether to go to a crying infant who is supposed to be sleeping, or not to go, because you want him to learn to put himself to sleep. If the potential for autism is a concern, the answer is clear: go to him, pick him up, and do whatever it takes to comfort him. You want him to learn to like human contact; a sort of opposite-of-autistic attitude, if you will. That's far more important than learning to put himself to sleep; it's not even close.

My latest son is almost 2 months old. We have been doing all of the above (though thankfully, the pregnancy was without any complications). At 2 months, it is impossible to know if he has autism or not. But the signs are encouraging, particularly his eye contact, which is frequent and often of significant duration.

Any or all of this could be disproved by science at some future time. But as science currently lacks answers, one has to form an opinion and go with it.