Any pregnant nurses out there?

So I work as a registered nurse in a busy ER in California. We seem to always be short staffed and therefore, don't get much help with lifting patients. Unfortunately, I feel that it is really looked down upon at my job to go on "light duty" while pregnant. So now I have no idea on what to do. Should I say something to my manager (who I've already told I'm pregnant), or just tough it out? My shifts are 12.5 hours (we are lucky if we get a half hour break). I am especially concerned because I've already had one shift where (10 hours into the shift) I started spotting. This happened after being on my feet all day and not getting much help with turning a patient.