I'm surprised that no one has mentioned this study yet. Perhaps Hypothyroid rates are skyrocketing and with it autism?
Autism four times likelier when mother's thyroid is weakened
Pregnant women who don't make nearly enough thyroid hormone are nearly 4 times likelier to produce autistic children than healthy women, report scientists from the Houston Methodist Neurological Institute and Erasmus Medical Centre in an upcoming Annals of Neurology.
The association emerged from a study of more than 4,000 Dutch mothers and their children, and it supports a growing view that autism spectrum disorders can be caused by a lack of maternal thyroid hormone, which past studies have shown is crucial to the migration of fetal brain cells during embryo development.