At my hospital they go with 38 weeks. I had to be induced with my first because of pre-eclampsia, but they wouldn't do it until I was past that 38 week mark (it was only a matter of a couple of days though). My SIL has been induced for her last 3 pregnancies and they wouldn't even book her in until she was past 37 weeks, so she would definitely be 38 weeks when she was induced.