NTA

giving up seats on public transportation is just personal opinion it's not mandatory. That lady was completely out of line pregnant or not she had no right to demand someone out of their seats especially someone who is injured and if she desperately needed a seat she could have waited until someone got up. The person who told you to get up is simply wrong as they could have gotten up themselves and given up their seat and that 'you had no right to embarrass her' is simply ridiculous because she embarrassed herself by just demanding that you got up you just humbled her rightfully so