Hi,

I wouldn't tell them - unless you think your line of work could be damaging to the baby or yourself. Nursing or factory work are two good examples of situations where its appropriate to tell them I think.
My sister got a temp job teaching when she was 4 months pg, and didn't tell them. She worked until about 7months I think? She felt guilty, but needed the money.
They are not allowed to discriminate, but lets face it - someone non-pregnant will probably be considered before you if they have the same quals and experience. Its just the way it happens!
Fi