It appears that the risk for having a child with Autism Spectrum Disorder (ASD) when you already have a child with ASD is quite a bit higher than previously thought.
In this article from Journal Watch, a physician edited site, a large size study (664 infants) is discussed.
Apparently previous studies have indicated that if a family has an older child with ASD, the chances of a subsequent child having Autism of some type were thought to be between 3 and 10%.
This new study shows that the number is 19%. I don’t like being an alarmist, but that is a big difference. The difference is because of the larger sample size and the fact that it’s been done over a longer period of time.