Greg, I totally agree with Trillian on this. There is a great youtube video someone posted the other day of women birthing large babies naturally - I will see if I can find the thread for you. It dispels the myths about women being unable to birth large babies (which is a myth, women have been doing this for many years!!).

Also, an u/s will not necessarily give you an accurate size. We have had many members have inductions and c/s due to babies that were shown to be large on the u/s - and then the babies were actually 7 or 8 pounds - not so big at all and all that unnecessary intervention!!

I say go with your instinct. If you are not keen on intervention, don't have it. You seem very well informed to me, good on you for that. I wish you and your wife all the very best.