I don't know what 3rd shift is but I work continental shifts (6 x 12hr shifts inclusive of days and nights) then 4 days off. I am 6 months pregnant and no harm done? I'm working right up too
I worked 3rd with my son. I'm a nurse, so it was very demanding. I had no complications at all tho. I think as long as you get plenty of rest you will be fine.