The idea was that certain autoimmune diseases may produce antibodies in the mother that, rather than protecting the fetus, attack the growing fetal brain. Pregnant rhesus monkeys injected with the antibodies found in ASD mothers (mothers of autistic children) had normal pregnancies and normal babies. But shortly after weaning they exhibited notable social and cognitive changes. Whether this is the rhesus version of autism needs to be confirmed.
But is it possible that Judy Van der Water at the University of California, Davis happened upon the basis for the spectrum disorders? I think it is.