Job is not pregnancy friendly..HELP!!!

So my job is far from physical but it is very demanding mentally, I have a new manager and CEO and they are not very considerate of my pregnancy. I am a salary employee and they want to overwork me. They have asked that I stay late, come in early and work on Saturdays on top of my 40 hours. It would not be so bad and frustrating if my manager was not putting his work load on top of what I already have. What can I do? I get stressed out and have sharp pains in my chest..I feel like a weak mama bc I know others have it worse but idk how much more stress I can handle at this job on top of my hour + drive home.