Im pregnant and i need a new job!?

Okay I recently got let go from my previous job, I am a certified medical assistant...I didn't tell them that I'm pregnant seeing that I am only about 10weeks pregnant...I need a job so bad to be able to raise this baby! My boyfriend is around but he has to finish his school and he can only work but so much...my questions are should I tell a potential employer that I am pregnant right away or should I wait and what rights do I have as a pregnant woman?? Please someone be able to give me good advice this is stressful!