I was on a packed commuter train once and in the silence this conversation happened
Seated guy (loudly): Are you pregnant?
Standing woman: Sorry?
Sg: I said are you pregnant?
Sw: No
Sg: Oh okay
The second hand cringey embarrassment of that interaction has stayed with me for about 25 years
I think it was done with the very best of intentions, what it taught me is that you should either just go ahead and give up your seat or hang on to it, it's the asking that makes things worse.
London transport introduced the little "baby on board" badges shortly after this, which simplified matters hugely.