At my last OB appointment, the doctor wrote on the prescription for the 19-week anatomy scan (which will be May 13) that I am due 10/10. My first thought was to wonder if my chart had been switched with someone else's. Then I realized that she was taking the last early measurement of the baby, which helps calculate the due date before the 8th week (when the size of babies are most consistent with their age) if the date of the last menstrual period is not known. For the record, if we go by the date of my last period, my due date is 10/4. If we go by my 7th week ultrasound measurements, my due date is 10/10. But this can't be...