Bio Oil is amazing stuff. I used it during pregancy, with a 9lb 11.5oz baby and had not one stretch mark!
I used it on my cesarean scar (she was too big to come out the proper way....and got stuck!!) and that is now practically gone - it certainly has no colour at all, just a little ripple on the skin, and my daughter has subsequently had to have major abdominal surgery....right from one side of her body to the other. She was operated on by the countries most prominant pediatric surgeon and he suggested Bio Oil.....her scar, after 7 months has pretty much completely disappeared.
It is fantastic stuff....ooh and I use it as a night cream...and my skin has never been better.