How many days is maternity leave in US?

Nancy • Pregnant with baby #1. I am 25 recently moved to the US
Hi girls. I am new in the US and I live in Michigan. Do you know haw many days before and after having the baby I could get at work? And when is it convenient to tell your boss and coworkers that you are pregnant. My job is very calm in an office so no worries about lifting or so. Thank you :)