Btw just incase your sis's dr's/MW's are like mine - my due date is 2 days later than Banda calculator. Im due 13th Dec according to Banda, but Dr says 15th. Most baby sites agree with banda but I was on one last week (possibly baby centre or cow and gate?) and they said 15th too.
My dr seems to be doing 40 weeks + 2 days or 9months +1 week from date of last period and not simply 40 weeks. I think it was the same for Caitlin. Very odd!!! x