
In the US it depends on the airline. We went on a babymoon vacation when my partner was 30-something weeks and didn’t need to provide any documentation (Alaska Airlines). She did run it by her providers first, but that wasn’t an airline/TSA/FAA requirement.
Telemarketers have been around for a long, long time (Wikipedia claim “…the practice of contacting potential customers by telephone originated in the late 19th century.”).
I personally recall a lot more telemarketing in the 90s, though I was a kid and just passed the phone to mom or dad. But that was also a time when caller ID was a luxury, and not everyone had answering machines.