How do i reduce the chances of having an autistic child?

No clear answer: We still do not know the myriad causes of autism, so beware anyone who tells you how to ensure you don't have a child with autism. Most of the known factors that increase your risk--genetics, in utero viral exposure, complicated delivery--are outside your control. Best advice: get good prenatal care and recognized your odds still excellent that your child will not have autism.

No specific actions: I do not know of any specific actions you can take to prevent autism other than not having a child by a mate who is autistic. There is nothing you can do to promote having a child with autism.