Has anyone ever heard of a connection between having certain viral infections while pregnant, and so causing autism in the baby?

Yes.: Exposure to the rubella virus during pregnancy definitely increases risk of autism (along with mamy other problems), and cytomegalovirus also may increase risk. This is quite different from the controversies about vaccines for viruses causing autism, which has repeatedly disproven.

It happens: Prenatal exposure to some viruses & substances can cause an epigenetic effect; i.e., they change the function, but not the structure, of some fetal genes. Researchers at the mind institute in davis, ca, have done animal studies with viruses. Autistic behaviors may be part of the resulting neurodevelopmental profile. Surveillance of all infants' development with screening tests is recommended.