Pregnancy discrimination ?

I’m kind of lost at what to do right now so my job is only giving me two days to get a medical clearance from my OB I’m pregnant and they said if I don’t get a medical clearance within the next two days they’re going to take me off to Work schedule Can they legally do that? I’ve been working my whole pregnancy. I’ve been trying to contact my OB and haven’t been able to get a hold of her or her medical assistant..  I called my job and told them I haven’t been able to get a hold of my OB and they said if I don’t have the medical clearance by the end of tomorrow, then I will be taken off the schedule. I am a caregiver. My job requires some lifting, and I understand the risk that I take, but I don’t feel that it’s fair for my job to take me off the schedule. If I don’t have a medical clearance within the next two days I am a single mom and I depend on the money I made to pay my bills.