I know a couple who did try the hanging upside down trick. It didn’t work thankfully because neither were fit to be parents.
My grandmother was one who got pregnant every year and a half. She had ten children while suffering from leukemia. That was before anyone knew what leukemia was.
If she had been healthy I expect she might have had fifteen kids.
I have three myself and they were a handful!
We had six in our family, and my dad was away for a lot of the early years at sea...how my mom managed...I don’t know.