Did they even do twilight sleep in the 70s? My grandmother said she had it, but my mom says it wasn't done when she had me (1973) - and this is the rual South so you'd think if they were still doing it anywhere, it would be small town hospitals.
Is she saying straight jacket and meaning some kind of binding? That's not uncommon for someone who has decided to stop breastfeeding (or not bf at all). I know in the 70s, women weren't encouraged to bf and there was a shot to dry up milk, which apparently made things quite painful for a few days, at least.
And people do forget the details. Thirty years on, who can say what any of us will remember? It's not ALWAYS a conspiracy, a lot of stuff happens between the birth of your children and the birth of your grandchildren. Nevermind that birth is often fast, confusing, intense, etc. It's easy to confuse details, I would think.