nope, I've never heard of needing one either. I drove myself to hospital after my waters broke last time...

You can ask for a medical certificate if you have had a ceasar and the seatbelt is too uncomfortable and that exempts you from seatbelt laws for a week or two, but I've never heard of before hand....nor would I go without a seatbelt no matter how uncomfortable...would rather not travel by car then.