Would they really let you go 42 weeks?

So I just went to the doctors I am 38 weeks and nothing!  in the doctors words "there's always next week". I asked how long will they let me go because all of the other doctors have said that the baby is big and I am measuring large blah blah blah. I have gone for like 7 ultrasounds to check the size. The doctors responds with, we won't do anything until 42 weeks! Are you kidding me!!!! Has anyone heard of this??? At 35 weeks when we confirmed she wasn't breach she was just short of 6lbs so by 42 weeks she would have to be over 10 lbs. ahhhh!!!!