Im aldo measuring behind and they are monitoring fetal development.... (I'm 27 werks)... they don't do that for everybody..BUT since this time around I have lakes of blood in my placenta and high blood pressure (both are associated with low birth weight) they want to make sure my baby girl is growing at the rate she should be... ive measured 5 days smaller from the beginning... I have another ultrasound today to see how she measures today :)
Yeah my Dr kept my due date the same and told me it was nothing to worry about. Let me know how your scan goes!
I think the time can vary a couple of days as long as they don't change your due date