Fooey. I weighed 105kgs when I fell pregnant (and weighed the same after I gave birth too interestingly, I'm 5'5) and I had a home waterbirth with the approval of my backup hospital, KEMH!. I honestly think this sort of stuff depends largely on who you end up with when you're in labour. But remember, they can't stop you from doing ANYTHING you want to so if you want to give birth in water, do so! By all means!