My obstetrician told me that steroids can be used throughout the pregnancy and are not harmful for the fetus apparently.
I take Depo-Medrol weekly (my adrenal gland will not function without it) and he said that we would continue those injections throughout the pregnancy.
However, the injections are not a large amount (equivelent to 3mg of prednisone daily).
Good luck and congrats
Julie