I just took on a second part-time job working at a retail store for the holiday season. I work three days a week at my primary job and the other three days I work at the retail store. I am 6 months pregnant and the retail store knew I was pregnant and working another job when they hired me. After working my first shift which was 8hrs I explained to my manager that I can't stand up that long at the register and that the max I could do was 3 hrs because my back starts to hurt. Well, today my manager told me that I have to work the day after Thanksgiving and I told her that I can't because I'm working at my other (primary) job that day. She said I had too and that I have to work 8hrs the following Saturday. Again I reminded her that I can't because I'm pregnant and I can't stand that long and once again she said I had too. My question is since they just hired me and I'm still on probation can they fire me if I don't comply?