How accurate is ultrasound due date?
The dates can be off if you conceived at an unpredictable time (in your case, if you conceived and then had a period), or if your baby is just above average in size. All the ultrasound does is give you dates based on average size/development. Being a couple of weeks off is not too strange. Your doctor will usually tell you if s/he is going to adjust your dates. Mine were so close together that they left it on my LMP, even though my first scan the baby was a few days smaller and since has been about a week bigger. I’m pretty sure that my first scan was the most accurate based on when I’m almost certain I ovluated.
