Pregnancy Discrimination

Has anyone had this happen to them while being pregnant?

I had to miss work yesterday because I have been really ill since finding out I am expecting. I have a doctors note as well for missing a 4 hour shift. I checked my schedule again for next week (which I had 25+ hours on the day before I called off) only to find that my manager has taken hours away from me. She has me scheduled for 8 hours now instead of the original 25 hours. I feel like I’m being punished for being pregnant. She has never done anything like this before. Is this pregnancy discrimination? I feel like it’s not right. I understand not showing up and needing the people etc. but she knows my situation and has told me in the past she would work with me. I’m just looking for some advice.