37 Weeks and People Still Expect the World

Now that I'm on maternity leave, everyone thinks now is a perfect time to ask me to give them rides, run errands for them, and do favors for them.
Nobody takes it seriously that my son will be here in 3 weeks or less and that I am currently carrying around 7 and a half pounds of life. Making a baby is no joke and quite frankly I'm mentally and physically exhausted.
I can't do this anymore but I don't know how to tell people no. I don't want anyone mad at me. And when I do reach my breaking point and tell someone no, they act like I'm such a bad person.