I am 7 months pregnant and start work at the end of this month. I live in Illinois and my due date is May 3. I want to know how do I let my job know that I am pregnant and will I be able to go on leave when I am due to have the baby.

Well, if you're 7 months pregnant, I think they're gonna know that when they see you. Whether or not you are eligible for any leave is up to the employer, unless you are in a state which requires maternity leave for employees of short tenure. You will not qualify for leave under FMLA because you will not have met the eligibility requirement.

I would be as up front as possible as soon as possible. If it isn't obvious when you start, it soon will be and most employers do not like surprises at the last minute. You can not be terminated because you are pregnant but you aren't given special consideration because you are. You get the same leave and treatment as any one else who has been there as long and who needs to be out for a medical reason.