That sort of info that is routinely collected, when studies involve prenatal/postnatal data.

I had older relatives who were obviously or probably autistic but were undiagnosed - because who had even heard of autism then. AHD meds and SSRI weren't yet a thing - but these folks mostly predated even Tricyclic ADs.

The linked article conclusion is that there is no real increase in the real rate of autism, only in the measurements.