I had heard 38-42 weeks. It's a general guide that things should be ok. But dont wish to have bubba out any sooner than when it naturally happens, whether that be 38 or 42 weeks, as I think it is a guideline as some baby's can be ready at 38 weeks and others not. My DD was born at 37+2days and she still had difficultys. Mind you nothing bad, jaundice and was very sleepy, had trouble with feeding due to sucking reflex not quite right and she took approx 1 1/2 hrs to feed. Yet she was still healthy in every other way.

Love