How could a 4-week discrepancy in due date be explained between calculated due date and the due date a doctor calculates after the first ultrasound?
For example, if we received the 12. of November as due date from our doc after the first ultrasound, this would put us in 7th week.
However, if we use the day of the first last period (e.g. 14. of January) the due date would be: 20. of October.
So how could such a discrepancy be explained?