Does short term disability cover pregnancy when I am unable to perform my job?

I work in healthcare and am required to lift upwards of 75 lbs on a daily basis (not every day but I work in home health so I have no one around to ist me usually). I am 6 wks pregnant now so I don't have my first OB appt for 2 wks and have not told my boss yet. I don't know what weight restrictions my OB will put me on and when, but I know she is not going to permit me to lift a 200 lb patient off a bed when I am 8 months along! I have short term disability benefits thru work. My job is not one where I can make it thru 9 months pregnant. It involves a lot of lifting and carrying heavy bags (as well as possible exposure to diseases like shingles). Will STD cover the time after my OB puts me on weight restrictions?