Pregnancy Date Discrepancy: Understanding Ultrasound Findings

Question
i am 34 yrs old i have 3 children and my last period was nov.23. i went for my 1st ultrasound yesterday and was told that judging from the size of the baby i was only 6weeks instead of 8 weeks pregnant she the heart rate was good it was 135 and everthing looked good she seemed to think i may have ovulated late. do you think this is correct or could something be wrong with the baby?

Answer
If your last period started on November 23, you should now be 8 weeks pregnant. If you are only 6 weeks by sonogram, you may be in error as to the first day of your last period, or you may have conceived later than expected. Bear in mind that a sonogram is not accurate until 15-20 weeks. I would repeat the sonogram at 20 weeks, at which time it will accurately confirm your due date and tell you how far pregnant you really are. I doubt  that anything is wrong with the baby.